code: def execute(self, env, args):
          
  
          # extract args
          old_task_name = args.old_task_name
          new_task_name = args.new_task_name
  
          if old_task_name == new_task_name:
              raise errors.FocusError(u'Could not rename task to itself')
  
          if env.task.active and env.task.name == old_task_name:
              raise errors.ActiveTask
  
          env.task.rename(old_task_name, new_task_name)
docs: Removes a task.
  
              `env`
                  Runtime ``Environment`` instance.
              `args`
                  Arguments object from arg parser.