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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 pull(self):
 """Enable or disable internal pull-up resistors for this pin. A value of digitalio.Pull.UP will enable a pull-up resistor, and None will disable it. Pull-down resistors are NOT supported! """

        if _get_bit(self._mcp.gppu, self._pin):
            return digitalio.Pull.UP
        return None