human
Solve the following python programming problem given the following code:
def repr_extractor(node) : 
    def makeReprOperator(operand, source_ref) : 
        return ExpressionOperationUnary (operator = 'Repr', operand = operand, source_ref = source_ref) 
return BuiltinOptimization.extractBuiltinArgs (node = node, builtin_class = <MASK>, builtin_spec = BuiltinOptimization.builtin_repr_spec) 
    
    Given the code above, what is a proper replacement for <MASK>? Choose among: node
assistant
#Here is a proper replacement for <MASK>.
def makeReprOperator(