0
     *
     * @example
     * ```
     * echo Carbon::parse('2018-07-25 12:45:16.334455')
     *   ->startOfSecond()
     *   ->format('H:i:s.u');
     * ```
     *
     * @return static
     */
    public function startOfSecond();

    /**
     * Resets the date to the first day of week (defined in $weekStartsAt) and the time to 00:00:00
     *
     * @example
     * ```
     * echo Carbon::parse('2018-07-25 12:45:16')->startOfWeek() . "\n";
     * echo Carbon::parse('2018-07-25 12:45:16')->locale('ar')->startOfWeek() . "\n";
     * echo Carbon::parse('2018-07-25 12:45:16')->startOfWeek(Carbon::SUNDAY) . "\n";
     * ```
     *
     * @param int $weekStartsAt optional start allow you to specify the day of week to use to start the week
     *
     * @return static
     */
    public function startOfWeek($weekStartsAt = null);

    /**
     * Resets the date to the first day of the year and the time to 00:00:00
     *
     * @example
     * ```
     * echo Carbon::parse('2018-07-25 12:45:16')->startOfYear();
     * ```
     *
     * @return static
     */
    public function startOfYear();

    /**
     * Subtract given units or interval to the current instance.
     *
     * @example $date->sub('hour', 3)
     * @example $date->sub(15, 'days')
     * @example $date->sub(CarbonInterval::days(4))
     *
     * @param string|DateInterval $unit
     * @param int                 $value
     * @param bool|null           $overflow
     *
     * @return static
     */
    public function sub($unit, $value = 1, $overflow = null);

    public function subRealUnit($unit, $value = 1);

    /**
     * Subtract given units to the current instance.
     *
     * @param string    $unit
     * @param int       $value
     * @param bool|null $overflow
     *
     * @return static
     */
    public function subUnit($unit, $value = 1, $overflow = null);

    /**
     * Subtract any unit to a new value without overflowing current other unit given.
     *
     * @param string $valueUnit    unit name to modify
     * @param int    $value        amount to subtract to the input unit
     * @param string $overflowUnit unit name to not overflow
     *
     * @return static
     */
    public function subUnitNoOverflow($valueUnit, $value, $overflowUnit);

    /**
     * Subtract given units or interval to the current instance.
     *
     * @see sub()
     *
     * @param string|DateInterval $unit
     * @param int                 $value
     * @param bool|null           $overflow
     *
     * @return static
     */
    public function subtract($unit, $value = 1, $overflow = null);

    /**
     * Get the difference in a human readable format in the current locale from current instance to an other
     * instance given (or now if null given).
     *
     * @return string
     */
    public function timespan($other = null, $timezone = null);

    /**
     * Set the instance's timestamp.
     *
     * @param int $value
     *
     * @return static
     */
    public function timestamp($value);

    /**
     * @alias setTimezone
     *
     * @param DateTimeZone|string $value
     *
     * @return static
     */
    public function timezone($value);

    /**
     * Get the difference in a human readable format in the current locale from an other
     * instance given (or now if null given) to current instance.
     *
     * When comparing a value in the past to default now:
     * 1 hour from now
     * 5 months from now
     *
     * When comparing a value in the future to default now:
     * 1 hour ago
     * 5 months ago
     *
     * When comparing a value in the past to another value:
     * 1 hour after
     * 5 months after
     *
     * When comparing a value in the future to another value:
     * 1 hour before
     * 5 months before
     *
     * @param Carbon|\DateTimeInterface|string|array|null $other   if array passed, will be used as parameters array, see $syntax below;
     *                                                             if null passed, now will be used as comparison reference;
     *                                                             if any other type, it will be converted to date and used as reference.
     * @param int|array                                   $syntax  if array passed, parameters will be extracted from it, the array may contains:
     *                                                             - 'syntax' entry (see below)
     *                                                             - 'short' entry (see below)
     *                                                             - 'parts' entry (see below)
     *                                                             - 'options' entry (see below)
     *                                                             - 'join' entry determines how to join multiple parts of the string
     *                                                             `  - if $join is a string, it's used as a joiner glue
     *                                                             `  - if $join is a callable/closure, it get the list of string and should return a string
     *                                                             `  - if $join is an array, the first item will be the default glue, and the second item
     *                                                             `    will be used instead of the glue for the last item
     *                                                             `  - if $join is true, it will be guessed from the locale ('list' translation file entry)
     *                                                             `  - if $join is missing, a space will be used as glue
     *                                                             - 'other' entry (see above)
     *                                                             if int passed, it add modifiers:
     *                                                             Possible values:
     *                                                             - CarbonInterface::DIFF_ABSOLUTE          no modifiers
     *                                                             - CarbonInterface::DIFF_RELATIVE_TO_NOW   add ago/from now modifier
     *                                                             - CarbonInterface::DIFF_RELATIVE_TO_OTHER add before/after modifier
     *                                                             Default value: CarbonInterface::DIFF_ABSOLUTE
     * @param bool                                        $short   displays short format of time units
     * @param int                                         $parts   maximum number of parts to display (default value: 1: single unit)
     * @param int                                         $options human diff options
     *
     * @return string
     */
    public function to($other = null, $syntax = null, $short = false, $parts = 1, $options = null);

    /**
     * Get default array representation.
     *
     * @example
     * ```
     * var_dump(Carbon::now()->toArray());
     * ```
     *
     * @return array
     */
    public function toArray();

    /**
     * Format the instance as ATOM
     *
     * @example
     * ```
     * echo Carbon::now()->toAtomString();
     * ```
     *
     * @return string
     */
    public function toAtomString();

    /**
     * Format the instance as COOKIE
     *
     * @example
     * ```
     * echo Carbon::now()->toCookieString();
     * ```
     *
     * @return string
     */
    public function toCookieString();

    /**
     * @alias toDateTime
     *
     * Return native DateTime PHP object matching the current instance.
     *
     * @example
     * ```
     * var_dump(Carbon::now()->toDate());
     * ```
     *
     * @return DateTime
     */
    public function toDate();

    /**
     * Format the instance as date
     *
     * @example
     * ```
     * echo Carbon::now()->toDateString();
     * ```
     *
     * @return string
     */
    public function toDateString();

    /**
     * Return native DateTime PHP object matching the current instance.
     *
     * @example
     * ```
     * var_dump(Carbon::now()->toDateTime());
     * ```
     *
     * @return DateTime
     */
    public function toDateTime();

    /**
     * Return native toDateTimeImmutable PHP object matching the current instance.
     *
     * @example
     * ```
     * var_dump(Carbon::now()->toDateTimeImmutable());
     * ```
     *
     * @return DateTimeImmutable
     */
    public function toDateTimeImmutable();

    /**
     * Format the instance as date and time T-separated with no timezone
     *
     * @example
     * ```
     * echo Carbon::now()->toDateTimeLocalString();
     * echo "\n";
     * echo Carbon::now()->toDateTimeLocalString('minute'); // You can specify precision among: minute, second, millisecond and microsecond
     * ```
     *
     * @param string $unitPrecision
     *
     * @return string
     */
    public function toDateTimeLocalString($unitPrecision = 'second');

    /**
     * Format the instance as date and time
     *
     * @example
     * ```
     * echo Carbon::now()->toDateTimeString();
     * ```
     *
     * @param string $unitPrecision
     *
     * @return string
     */
    public function toDateTimeString($unitPrecision = 'second');

    /**
     * Format the instance with day, date and time
     *
     * @example
     * ```
     * echo Carbon::now()->toDayDateTimeString();
     * ```
     *
     * @return string
     */
    public function toDayDateTimeString();

    /**
     * Format the instance as a readable date
     *
     * @example
     * ```
     * echo Carbon::now()->toFormattedDateString();
     * ```
     *
     * @return string
     */
    public function toFormattedDateString();

    /**
     * Return the ISO-8601 string (ex: 1977-04-22T06:00:00Z, if $keepOffset truthy, offset will be kept:
     * 1977-04-22T01:00:00-05:00).
     *
     * @example
     * ```
     * echo Carbon::now('America/Toronto')->toISOString() . "\n";
     * echo Carbon::now('America/Toronto')->toISOString(true) . "\n";
     * ```
     *
     * @param bool $keepOffset Pass true to keep the date offset. Else forced to UTC.
     *
     * @return null|string
     */
    public function toISOString($keepOffset = false);

    /**
     * Return a immutable copy of the instance.
     *
     * @return CarbonImmutable
     */
    public function toImmutable();

    /**
     * Format the instance as ISO8601
     *
     * @example
     * ```
     * echo Carbon::now()->toIso8601String();
     * ```
     *
     * @return string
     */
    public function toIso8601String();

    /**
     * Convert the instance to UTC and return as Zulu ISO8601
     *
     * @example
     * ```
     * echo Carbon::now()->toIso8601ZuluString();
     * ```
     *
     * @param string $unitPrecision
     *
     * @return string
     */
    public function toIso8601ZuluString($unitPrecision = 'second');

    /**
     * Return the ISO-8601 string (ex: 1977-04-22T06:00:00Z) with UTC timezone.
     *
     * @example
     * ```
     * echo Carbon::now('America/Toronto')->toJSON();
     * ```
     *
     * @return null|string
     */
    public function toJSON();

    /**
     * Return a mutable copy of the instance.
     *
     * @return Carbon
     */
    public function toMutable();

    /**
     * Get the difference in a human readable format in the current locale from an other
     * instance given to now
     *
     * @param int|array $syntax  if array passed, parameters will be extracted from it, the array may contains:
     *                           - 'syntax' entry (see below)
     *                           - 'short' entry (see below)
     *                           - 'parts' entry (see below)
     *                           - 'options' entry (see below)
     *                           - 'join' entry determines how to join multiple parts of the string
     *                           `  - if $join is a string, it's used as a joiner glue
     *                           `  - if $join is a callable/closure, it get the list of string and should return a string
     *                           `  - if $join is an array, the first item will be the default glue, and the second item
     *                           `    will be used instead of the glue for the last item
     *                           `  - if $join is true, it will be guessed from the locale ('list' translation file entry)
     *                           `  - if $join is missing, a space will be used as glue
     *                           if int passed, it add modifiers:
     *                           Possible values:
     *                           - CarbonInterface::DIFF_ABSOLUTE          no modifiers
     *                           - CarbonInterface::DIFF_RELATIVE_TO_NOW   add ago/from now modifier
     *                           - CarbonInterface::DIFF_RELATIVE_TO_OTHER add before/after modifier
     *                           Default value: CarbonInterface::DIFF_ABSOLUTE
     * @param bool      $short   displays short format of time units
     * @param int       $parts   maximum number of parts to display (default value: 1: single part)
     * @param int       $options human diff options
     *
     * @return string
     */
    public function toNow($syntax = null, $short = false, $parts = 1, $options = null);

    /**
     * Get default object representation.
     *
     * @example
     * ```
     * var_dump(Carbon::now()->toObject());
     * ```
     *
     * @return object
     */
    public function toObject();

    /**
     * Create a iterable CarbonPeriod object from current date to a given end date (and optional interval).
     *
     * @param \DateTimeInterface|Carbon|CarbonImmutable|int|null $end      period end date or recurrences count if int
     * @param int|\DateInterval|string|null                      $interval period default interval or number of the given $unit
     * @param string|null                                        $unit     if specified, $interval must be an integer
     *
     * @return CarbonPeriod
     */
    public function toPeriod($end = null, $interval = null, $unit = null);

    /**
     * Format the instance as RFC1036
     *
     * @example
     * ```
     * echo Carbon::now()->toRfc1036String();
     * ```
     *
     * @return string
     */
    public function toRfc1036String();

    /**
     * Format the instance as RFC1123
     *
     * @example
     * ```
     * echo Carbon::now()->toRfc1123String();
     * ```
     *
     * @return string
     */
    public function toRfc1123String();

    /**
     * Format the instance as RFC2822
     *
     * @example
     * ```
     * echo Carbon::now()->toRfc2822String();
     * ```
     *
     * @return string
     */
    public function toRfc2822String();

    /**
     * Format the instance as RFC3339
     *
     * @example
     * ```
     * echo Carbon::now()->toRfc3339String();
     * ```
     *
     * @return string
     */
    public function toRfc3339String();

    /**
     * Format the instance as RFC7231
     *
     * @example
     * ```
     * echo Carbon::now()->toRfc7231String();
     * ```
     *
     * @return string
     */
    public function toRfc7231String();

    /**
     * Format the instance as RFC822
     *
     * @example
     * ```
     * echo Carbon::now()->toRfc822String();
     * ```
     *
     * @return string
     */
    public function toRfc822String();

    /**
     * Format the instance as RFC850
     *
     * @example
     * ```
     * echo Carbon::now()->toRfc850String();
     * ```
     *
     * @return string
     */
    public function toRfc850String();

    /**
     * Format the instance as RSS
     *
     * @example
     * ```
     * echo Carbon::now()->toRssString();
     * ```
     *
     * @return string
     */
    public function toRssString();

    /**
     * Returns english human readable complete date string.
     *
     * @example
     * ```
     * echo Carbon::now()->toString();
     * ```
     *
     * @return string
     */
    public function toString();

    /**
     * Format the instance as time
     *
     * @example
     * ```
     * echo Carbon::now()->toTimeString();
     * ```
     *
     * @param string $unitPrecision
     *
     * @return string
     */
    public function toTimeString($unitPrecision = 'second');

    /**
     * Format the instance as W3C
     *
     * @example
     * ```
     * echo Carbon::now()->toW3cString();
     * ```
     *
     * @return string
     */
    public function toW3cString();

    /**
     * Create a Carbon instance for today.
     *
     * @param \DateTimeZone|string|null $tz
     *
     * @return static
     */
    public static function today($tz = null);

    /**
     * Create a Carbon instance for tomorrow.
     *
     * @param \DateTimeZone|string|null $tz
     *
     * @return static
     */
    public static function tomorrow($tz = null);

    /**
     * Translate using translation string or callback available.
     *
     * @param string                                             $key
     * @param array                                              $parameters
     * @param null                                               $number
     * @param \Symfony\Component\Translation\TranslatorInterface $translator
     *
     * @return string
     */
    public function translate(string $key, array $parameters = [], $number = null, \Symfony\Component\Translation\TranslatorInterface $translator = null, bool $altNumbers = false): string;

    /**
     * Returns the alternative number for a given integer if available in the current locale.
     *
     * @param int $number
     *
     * @return string
     */
    public function translateNumber(int $number): string;

    /**
     * Translate a time string from a locale to an other.
     *
     * @param string      $timeString time string to translate
     * @param string|null $from       input locale of the $timeString parameter (`Carbon::getLocale()` by default)
     * @param string|null $to         output locale of the result returned (`"en"` by default)
     * @param int         $mode       specify what to translate with options:
     *                                - CarbonInterface::TRANSLATE_ALL (default)
     *                                - CarbonInterface::TRANSLATE_MONTHS
     *                                - CarbonInterface::TRANSLATE_DAYS
     *                                - CarbonInterface::TRANSLATE_UNITS
     *                                - CarbonInterface::TRANSLATE_MERIDIEM
     *                                You can use pipe to group: CarbonInterface::TRANSLATE_MONTHS | CarbonInterface::TRANSLATE_DAYS
     *
     * @return string
     */
    public static function translateTimeString($timeString, $from = null, $to = null, $mode = 15);

    /**
     * Translate a time string from the current locale (`$date->locale()`) to an other.
     *
     * @param string      $timeString time string to translate
     * @param string|null $to         output locale of the result returned ("en" by default)
     *
     * @return string
     */
    public function translateTimeStringTo($timeString, $to = null);

    /**
     * Translate using translation string or callback available.
     *
     * @param \Symfony\Component\Translation\TranslatorInterface $translator
     * @param string                                             $key
     * @param array                                              $parameters
     * @param null                                               $number
     *
     * @return string
     */
    public static function translateWith(\Symfony\Component\Translation\TranslatorInterface $translator, string $key, array $parameters = [], $number = null): string;

    /**
     * Format as ->format() do (using date replacements patterns from http://php.net/manual/fr/function.date.php)
     * but translate words whenever possible (months, day names, etc.) using the current locale.
     *
     * @param string $format
     *
     * @return string
     */
    public function translatedFormat(string $format): string;

    /**
     * Set the timezone or returns the timezone name if no arguments passed.
     *
     * @param DateTimeZone|string $value
     *
     * @return static|string
     */
    public function tz($value = null);

    /**
     * @alias getTimestamp
     *
     * Returns the UNIX timestamp for the current date.
     *
     * @return int
     */
    public function unix();

    /**
     * @alias to
     *
     * Get the difference in a human readable format in the current locale from an other
     * instance given (or now if null given) to current instance.
     *
     * @param Carbon|\DateTimeInterface|string|array|null $other   if array passed, will be used as parameters array, see $syntax below;
     *                                                             if null passed, now will be used as comparison reference;
     *                                                             if any other type, it will be converted to date and used as reference.
     * @param int|array                                   $syntax  if array passed, parameters will be extracted from it, the array may contains:
     *                                                             - 'syntax' entry (see below)
     *                                                             - 'short' entry (see below)
     *                                                             - 'parts' entry (see below)
     *                                                             - 'options' entry (see below)
     *                                                             - 'join' entry determines how to join multiple parts of the string
     *                                                             `  - if $join is a string, it's used as a joiner glue
     *                                                             `  - if $join is a callable/closure, it get the list of string and should return a string
     *                                                             `  - if $join is an array, the first item will be the default glue, and the second item
     *                                                             `    will be used instead of the glue for the last item
     *                                                             `  - if $join is true, it will be guessed from the locale ('list' translation file entry)
     *                                                             `  - if $join is missing, a space will be used as glue
     *                                                             - 'other' entry (see above)
     *                                                             if int passed, it add modifiers:
     *                                                             Possible values:
     *                                                             - CarbonInterface::DIFF_ABSOLUTE          no modifiers
     *                                                             - CarbonInterface::DIFF_RELATIVE_TO_NOW   add ago/from now modifier
     *                                                             - CarbonInterface::DIFF_RELATIVE_TO_OTHER add before/after modifier
     *                                                             Default value: CarbonInterface::DIFF_ABSOLUTE
     * @param bool                                        $short   displays short format of time units
     * @param int                                         $parts   maximum number of parts to display (default value: 1: single unit)
     * @param int                                         $options human diff options
     *
     * @return string
     */
    public function until($other = null, $syntax = null, $short = false, $parts = 1, $options = null);

    /**
     * @deprecated To avoid conflict between different third-party libraries, static setters should not be used.
     *             You should rather use the ->settings() method.
     *             Or you can use method variants: addMonthsWithOverflow/addMonthsNoOverflow, same variants
     *             are available for quarters, years, decade, centuries, millennia (singular and plural forms).
     * @see settings
     *
     * Indicates if months should be calculated with overflow.
     *
     * @param bool $monthsOverflow
     *
     * @return void
     */
    public static function useMonthsOverflow($monthsOverflow = true);

    /**
     * @deprecated To avoid conflict between different third-party libraries, static setters should not be used.
     *             You should rather use the ->settings() method.
     * @see settings
     *
     * Enable the strict mode (or disable with passing false).
     *
     * @param bool $strictModeEnabled
     */
    public static function useStrictMode($strictModeEnabled = true);

    /**
     * @deprecated To avoid conflict between different third-party libraries, static setters should not be used.
     *             You should rather use the ->settings() method.
     *             Or you can use method variants: addYearsWithOverflow/addYearsNoOverflow, same variants
     *             are available for quarters, years, decade, centuries, millennia (singular and plural forms).
     * @see settings
     *
     * Indicates if years should be calculated with overflow.
     *
     * @param bool $yearsOverflow
     *
     * @return void
     */
    public static function useYearsOverflow($yearsOverflow = true);

    /**
     * Set the instance's timezone to UTC.
     *
     * @return static
     */
    public function utc();

    /**
     * Returns the minutes offset to UTC if no arguments passed, else set the timezone with given minutes shift passed.
     *
     * @param int|null $offset
     *
     * @return int|static
     */
    public function utcOffset(int $offset = null);

    /**
     * Returns the milliseconds timestamps used amongst other by Date javascript objects.
     *
     * @return float
     */
    public function valueOf();

    /**
     * Get/set the week number using given first day of week and first
     * day of year included in the first week. Or use US format if no settings
     * given (Sunday / Jan 6).
     *
     * @param int|null $week
     * @param int|null $dayOfWeek
     * @param int|null $dayOfYear
     *
     * @return int|static
     */
    public function week($week = null, $dayOfWeek = null, $dayOfYear = null);

    /**
     * Set/get the week number of year using given first day of week and first
     * day of year included in the first week. Or use US format if no settings
     * given (Sunday / Jan 6).
     *
     * @param int|null $year      if null, act as a getter, if not null, set the year and return current instance.
     * @param int|null $dayOfWeek first date of week from 0 (Sunday) to 6 (Saturday)
     * @param int|null $dayOfYear first day of year included in the week #1
     *
     * @return int|static
     */
    public function weekYear($year = null, $dayOfWeek = null, $dayOfYear = null);

    /**
     * Get/set the weekday from 0 (Sunday) to 6 (Saturday).
     *
     * @param int|null $value new value for weekday if using as setter.
     *
     * @return static|int
     */
    public function weekday($value = null);

    /**
     * Get the number of weeks of the current week-year using given first day of week and first
     * day of year included in the first week. Or use US format if no settings
     * given (Sunday / Jan 6).
     *
     * @param int|null $dayOfWeek first date of week from 0 (Sunday) to 6 (Saturday)
     * @param int|null $dayOfYear first day of year included in the week #1
     *
     * @return int
     */
    public function weeksInYear($dayOfWeek = null, $dayOfYear = null);

    /**
     * Create a Carbon instance for yesterday.
     *
     * @param \DateTimeZone|string|null $tz
     *
     * @return static
     */
    public static function yesterday($tz = null);

    // </methods>
}