code: def call(self, method, params, callback=None):
          
          cur_id = self._next_id()
          if callback:
              self._callbacks[cur_id] = callback
          self.send({'msg': 'method', 'id': cur_id, 'method': method, 'params': params})
docs: Call a method on the server
  
          Arguments:
          method - the remote server method
          params - an array of commands to send to the method
  
          Keyword Arguments:
          callback - a callback function containing the return data