code: public static function startsWith($s, $prefix, $caseInsensitive = false)
      {
          // substr_compare errors if $main_str is zero-length, so handle that
          // case specially here.
          if (\strlen($s) == 0) {
              return strlen($prefix) == 0;
          }
  
          return \substr_compare($s, $prefix, 0, strlen($prefix), $caseInsensitive) == 0;
      }
docs: Return whether `$s` starts with `$prefix`.
  
  @param string $s
  @param string $prefix
  @param bool $caseInsensitive
  
  @return bool