code: def get_lastfunction_header(self, header, default_return_value=None):
          
          if self._last_call is None:
              raise TwythonError('This function must be called after an API call. \
                                 It delivers header information.')
  
          return self._last_call['headers'].get(header, default_return_value)
docs: Returns a specific header from the last API call
          This will return None if the header is not present
  
          :param header: (required) The name of the header you want to get
                         the value of
  
          Most useful for the following header information:
              x-rate-limit-limit,
              x-rate-limit-remaining,
              x-rate-limit-class,
              x-rate-limit-reset