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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 close(self):
 """Close a port on dummy_serial."""

        if VERBOSE:
            _print_out('\nDummy_serial: Closing port\n')

        if not self._isOpen:
            raise IOError('Dummy_serial: The port is already closed')
            
        self._isOpen = False
        self.port = None