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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def remove_watcher(self, fd):
 """Stops watching a fd."""

        if not isinstance(fd, int):
            fd = fd.fileno()

        if fd not in self.callbacks:
            return

        self.callbacks.pop(fd, None)
        self.epoll.unregister(fd)