def on_name(self, node):    # ('id', 'ctx')
        """Name node."""
        ctx = node.ctx.__class__
        if ctx in (ast.Param, ast.Del):
            return str(node.id)
        else:
            if node.id in self.symtable:
                return self.symtable[node.id]
            else:
                msg = "name '%s' is not defined" % node.id
                self.raise_exception(node, exc=NameError, msg=msg)