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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_callback(self, handle):
 """Remove a callback."""

        if self._poll is None:
            raise RuntimeError('poll instance is closed')
        remove_callback(self, handle)
        if handle.extra & READABLE:
            self._readers -= 1
        if handle.extra & WRITABLE:
            self._writers -= 1
        self._sync()