original_string: public function keys()
      {
          return $this->create(array_keys($this->toArray()))->map(
              function ($key) {
                  return new String($key);
              }
          );
      }
code: public function keys()
      {
          return $this->create(array_keys($this->toArray()))->map(
              function ($key) {
                  return new String($key);
              }
          );
      }
code_tokens: public function keys ( ) { return $ this -> create ( array_keys ( $ this -> toArray ( ) ) ) -> map ( function ( $ key ) { return new String ( $ key ) ; } ) ; }
docstring: Get the array keys
  
  @return Hash[String] containing the keys
docstring_tokens: Get the array keys