docs: def append(self, row):
          """
          Appends a row to the list. Takes a dictionary, returns a row.
          """
          if isinstance(row, dict):
              row = self.Row(row)
          elif isinstance(row, self.Row):
              pass
          elif isinstance(row, SharePointListRow):
              raise TypeError("row must be a dict or an instance of SharePointList.Row, not SharePointListRow")
          else:
              raise TypeError("row must be a dict or an instance of SharePointList.Row")
          self.rows  # Make sure self._rows exists.
          self._rows.append(row)
          return row