code: def validate(self):
          
          _validate_operator_name(self.operator, UnaryTransformation.SUPPORTED_OPERATORS)
  
          if not isinstance(self.inner_expression, Expression):
              raise TypeError(u'Expected Expression inner_expression, got {} {}'.format(
                  type(self.inner_expression).__name__, self.inner_expression))
docs: Validate that the UnaryTransformation is correctly representable.