def _convert_to_python(self, value, state):
        address = value.replace(':', '').lower()  # remove colons
        if len(address) != 12:
            raise Invalid(
                self.message('badLength', state,
                    length=len(address)), address, state)
        for char in address:
            if self.valid_characters not in char:
                raise Invalid(
                    self.message('badCharacter', state,
                        char=char), address, state)
        if self.add_colons:
            address = '%s:%s:%s:%s:%s:%s' % (
                address[0:2], address[2:4], address[4:6],
                address[6:8], address[8:10], address[10:12])
        return address
dataset/ETHPy150Open formencode/formencode/formencode/validators.py/MACAddress._convert_to_python/swapped operands of `not in`