original_string: private static function isValidTimezone(string $timezone): bool
      {
          // @codeCoverageIgnoreStart
          if (self::$timezones === null) {
              self::$timezones = [];
              foreach (timezone_identifiers_list() as $zone) {
                  self::$timezones[$zone] = true;
              }
          }
          // @codeCoverageIgnoreEnd
  
          return isset(self::$timezones[$timezone]);
      }
code: private static function isValidTimezone(string $timezone): bool
      {
          // @codeCoverageIgnoreStart
          if (self::$timezones === null) {
              self::$timezones = [];
              foreach (timezone_identifiers_list() as $zone) {
                  self::$timezones[$zone] = true;
              }
          }
          // @codeCoverageIgnoreEnd
  
          return isset(self::$timezones[$timezone]);
      }
code_tokens: private static function isValidTimezone ( string $ timezone ) : bool { // @codeCoverageIgnoreStart if ( self :: $ timezones === null ) { self :: $ timezones = [ ] ; foreach ( timezone_identifiers_list ( ) as $ zone ) { self :: $ timezones [ $ zone ] = true ; } } // @codeCoverageIgnoreEnd return isset ( self :: $ timezones [ $ timezone ] ) ; }
docstring: Checks if a timezone string is valid
  
  @param string $timezone The timezone string
  
  @return bool
docstring_tokens: Checks if a timezone string is valid