def feedback(self, diagnostic=None):
        """
        Do feedback. Write infos into diagnostic object, if this parameter
        is not provide and self is a AST (has is own diagnostic object),
        use the diagnostic of self.
        """
        # get algo
        type_algo = self.type_algos()
        if diagnostic is None and hasattr(self, 'diagnostic'):
            diagnostic = self.diagnostic
        type_algo[2](diagnostic)