docs: def _get_params(self, rdata):
          """
          Returns a list of jsonrpc request's method parameters.
          """
          if 'params' in rdata:
              if isinstance(rdata['params'], dict) \
                      or isinstance(rdata['params'], list) \
                      or rdata['params'] is None:
                  return rdata['params']
              else:
                  # wrong type
                  raise InvalidRequestError
          else:
              return None