code: def add_task_to_diagram(self, process_id, task_name="", node_id=None):
          
          return self.add_flow_node_to_diagram(process_id, consts.Consts.task, task_name, node_id)
docs: Adds a Task element to BPMN diagram.
          User-defined attributes:
  
          - name
  
  
          :param process_id: string object. ID of parent process,
          :param task_name: string object. Name of task,
          :param node_id: string object. ID of node. Default value - None.
          :return: a tuple, where first value is task ID, second a reference to created object.