Python "socket" library - where is real implementation? [duplicate]

When i searched implementation of listen method in _socket.pyi i founded only this code with ellipsis:

class socket:
    # ... some another methods with ellipsis ...
    def listen(self, __backlog: int = ...) -> None: ...

I could not find a real implementation of listen(). What is this pattern when methods without explicit implementation are used in the main class of the module? What is the point of this approach?