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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 _pi_id(self):
 """Try to detect id of a Raspberry Pi."""

        # Check for Pi boards:
        pi_rev_code = self._pi_rev_code()
        if pi_rev_code:
            for model, codes in _PI_REV_CODES.items():
                if pi_rev_code in codes:
                    return model
        return None