docs: def previous_error(self):
          """**DEPRECATED**: Get the most recent error on this database.
  
          This method is obsolete: all MongoDB write operations (insert, update,
          remove, and so on) use the write concern ``w=1`` and report their
          errors by default.
  
          Only returns errors that have occurred since the last call to
          :meth:`reset_error_history`. Returns None if no such errors have
          occurred.
  
          .. versionchanged:: 2.8
             Deprecated.
          """
          warnings.warn("previous_error() is deprecated",
                        DeprecationWarning, stacklevel=2)
  
          error = self.command("getpreverror")
          if error.get("err", 0) is None:
              return None
          return error