Django：发送信号 - 不理解文档

I have 2 listeners defined:

我定义了两个听众:

def update_dashbaord_modified_date(sender, **kwargs):
    """Listen for changes to Goal, Action, etc. since we
    want to update the date modified on Dashbaord when a change occurs."""
    ... do something ...

post_save.connect(update_dashbaord_modified_date) # Register to listen for post_save signals
post_delete.connect(update_dashbaord_modified_date) # Register to listen for post_delete signals
def u