PyQt5 pyqtSignal类 有没有前辈介绍一下

class pyqtSignal(object):
def call(self, *args, **kwargs): # real signature unknown
""" Call self as a function. """
pass

def __getitem__(self, *args, **kwargs): # real signature unknown
    """ Return self[key]. """
    pass

def __get__(self, *args, **kwargs): # real signature unknown
    """ Return an attribute of instance, which is of type owner. """
    pass

def __init__(self, *args, **kwargs): # real signature unknown
    pass

@staticmethod # known case of __new__
def __new__(*args, **kwargs): # real signature unknown
    """ Create and return a new object.  See help(type) for accurate signature. """
    pass

def __repr__(self, *args, **kwargs): # real signature unknown
    """ Return repr(self). """
    pass

都是pass，只有接口，没有实现具体功能。