input: Write a python function to delete a task by its ID.
  assert os.path.exists(os.path.join('~/jsub/', '1')) == False
  assert os.path.exists(os.path.join('~/jsub/', '2')) == False
  assert os.path.exists(os.path.join('~/jsub/', '3')) == False
output: import os
  
  def delete_task_by_id(task_id):
      task_path = os.path.join(os.path.expanduser('~'), 'jsub', str(task_id))
      if os.path.exists(task_path):
          os.remove(task_path)