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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 unwrap(self, value, session=None):
        ''' Unwrap value using the unwrap function from ``EnumField.item_type``.
            Since unwrap validation could not happen in is_valid_wrap, it
            happens in this function.'''
        self.validate_unwrap(value)
        value = self.item_type.unwrap(value, session=session)
        for val in self.values:
            if val == value:
                return val
        self._fail_validation(value, 'Value was not in the enum values')