docs: def _disconnect(self):
          """Disconnect from all MongoDB Clients."""
          for cluster in self._clusters:
              if 'connection' in cluster:
                  connection = cluster.pop('connection')
                  connection.close()
          # Remove all attributes that are database names so that next time
          # when they are accessed, __getattr__ will be called and will create
          # new Clients
          for dbname in self._mapped_databases:
              self.__delattr__(dbname)
          self._mapped_databases = []