code: function cancelTask(proc, taskId) {
    const taskProcs = proc.tasks[taskId];
    delete proc.tasks[taskId];
  
    for (const execId in taskProcs) {
      const taskCall = taskProcs[execId];
      if (taskCall && taskCall.cancel) {
        taskCall.cancel();
      }
    }
  }
docs: Cancel task with given id in the process if exists
  and can be cancelled (have `cancel` function defined)
  
  @private
  @param  {Process} proc
  @param  {nubmer} id