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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 unregister_key_binding(self, keydef):
 """Unregister a key binding by keydef."""

        binding_name = MPV._binding_name(keydef)
        self.command('disable-section', binding_name)
        self.command('define-section', binding_name, '')
        if binding_name in self._key_binding_handlers:
            del self._key_binding_handlers[binding_name]
            if not self._key_binding_handlers:
                self.unregister_message_handler('key-binding')