original_string: protected function nUrlScheme($scheme)
      {
          if (!($scheme = (string) $scheme)) {
              return $scheme; // Nothing to do.
          }
          if (mb_strpos($scheme, ':') !== false) {
              $scheme = strstr($scheme, ':', true);
          }
          return mb_strtolower($scheme);
      }
code: protected function nUrlScheme($scheme)
      {
          if (!($scheme = (string) $scheme)) {
              return $scheme; // Nothing to do.
          }
          if (mb_strpos($scheme, ':') !== false) {
              $scheme = strstr($scheme, ':', true);
          }
          return mb_strtolower($scheme);
      }
code_tokens: protected function nUrlScheme ( $ scheme ) { if ( ! ( $ scheme = ( string ) $ scheme ) ) { return $ scheme ; // Nothing to do. } if ( mb_strpos ( $ scheme , ':' ) !== false ) { $ scheme = strstr ( $ scheme , ':' , true ) ; } return mb_strtolower ( $ scheme ) ; }
docstring: Normalizes a URL scheme.
  
  @since 140417 Initial release.
  
  @param string $scheme An input URL scheme.
  
  @return string A normalized URL scheme (always lowercase).
docstring_tokens: Normalizes a URL scheme .