$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());
     * ```
     */
    public function toArray(): array;

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

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

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

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

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

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

    /**
     * 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
     * ```
     */
    public function toDateTimeLocalString(string $unitPrecision = 'second'): string;

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

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

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

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

    /**
     * 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.
     */
    public function toISOString(bool $keepOffset = false): ?string;

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

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

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

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

    /**
     * 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());
     * ```
     */
    public function toObject(): object;

    /**
     * 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, $interval must be an integer
     */
    public function toPeriod($end = null, $interval = null, $unit = null): CarbonPeriod;

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

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

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

    /**
     * Format the instance as RFC3339.
     *
     * @example
     * ```
     * echo Carbon::now()->toRfc3339String() . "\n";
     * echo Carbon::now()->toRfc3339String(true) . "\n";
     * ```
     */
    public function toRfc3339String(bool $extended = false): string;

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

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

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

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

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

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

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

    /**
     * Create a Carbon instance for today.
     */
    public static function today(DateTimeZone|string|int|null $timezone = null): static;

    /**
     * Create a Carbon instance for tomorrow.
     */
    public static function tomorrow(DateTimeZone|string|int|null $timezone = null): static;

    /**
     * Translate using translation string or callback available.
     *
     * @param string                   $key        key to find
     * @param array                    $parameters replacement parameters
     * @param string|int|float|null    $number     number if plural
     * @param TranslatorInterface|null $translator an optional translator to use
     * @param bool                     $altNumbers pass true to use alternative numbers
     *
     * @return string
     */
    public function translate(string $key, array $parameters = [], string|int|float|null $number = null, ?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 date/time/duration string to translate (may also contain English)
     * @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:
     *                                - self::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(string $timeString, ?string $from = null, ?string $to = null, int $mode = self::TRANSLATE_ALL): string;

    /**
     * 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(string $timeString, ?string $to = null): string;

    /**
     * Translate using translation string or callback available.
     *
     * @param TranslatorInterface $translator an optional translator to use
     * @param string              $key        key to find
     * @param array               $parameters replacement parameters
     * @param int|float|null      $number     number if plural
     *
     * @return string
     */
    public static function translateWith(TranslatorInterface $translator, string $key, array $parameters = [], $number = null): string;

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

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

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

    /**
     * @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(bool $monthsOverflow = true): void;

    /**
     * @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(bool $strictModeEnabled = true): void;

    /**
     * @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(bool $yearsOverflow = true): void;

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

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

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

    /**
     * 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 WeekDay|int|null $value new value for weekday if using as setter.
     */
    public function weekday(WeekDay|int|null $value = null): static|int;

    /**
     * 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);

    /**
     * Temporarily sets a static date to be used within the callback.
     * Using setTestNow to set the date, executing the callback, then
     * clearing the test instance.
     *
     * /!\ Use this method for unit tests only.
     *
     * @template T
     *
     * @param DateTimeInterface|Closure|static|string|false|null $testNow  real or mock Carbon instance
     * @param Closure(): T                                       $callback
     *
     * @return T
     */
    public static function withTestNow(mixed $testNow, callable $callback): mixed;

    /**
     * Create a Carbon instance for yesterday.
     */
    public static function yesterday(DateTimeZone|string|int|null $timezone = null): static;

    // </methods>
}