Find arguments that should accumulate values and fix them.

def fix_list_arguments(self):
        """Find arguments that should accumulate values and fix them."""
        either = [list(c.children) for c in self.either.children]
        for case in either:
            case = [c for c in case if case.count(c) > 1]
            for a in [e for e in case if type(e) == Argument]:
                a.value = []
        return self