code: def to_api_data(self, restrict_keys=None):
          
          cc = self._cc  # alias
          data = {
              cc('column_hidden'): self._column_hidden,
              cc('row_hidden'): self._row_hidden,
              cc('formulas'): self._formulas,
              cc('formulas_local'): self._formulas_local,
              cc('formulas_r1_c1'): self._formulas_r1_c1,
              cc('number_format'): self._number_format,
              cc('values'): self._values,
          }
  
          if restrict_keys:
              for key in list(data.keys()):
                  if key not in restrict_keys:
                      del data[key]
          return data
docs: Returns a dict to communicate with the server
  
          :param restrict_keys: a set of keys to restrict the returned data to
          :rtype: dict