code: def show_warnings(self):
          
          if self._server_version < (4,1): return ()
          self.query("SHOW WARNINGS")
          r = self.store_result()
          warnings = r.fetch_row(0)
          return warnings
docs: Return detailed information about warnings as a
          sequence of tuples of (Level, Code, Message). This
          is only supported in MySQL-4.1 and up. If your server
          is an earlier version, an empty sequence is returned.