How to use the executing.executing.QualnameVisitor function in executing

self._nodes_by_line = defaultdict(list)
        self.tree = None
        self._qualnames = {}

        try:
            self.tree = ast.parse(ast_text, filename=filename)
        except SyntaxError:
            pass
        else:
            for node in ast.walk(self.tree):
                for child in ast.iter_child_nodes(node):
                    child.parent = node
                if hasattr(node, 'lineno'):
                    self._nodes_by_line[node.lineno].append(node)

            visitor = QualnameVisitor()
            visitor.visit(self.tree)
            self._qualnames = visitor.qualnames

def __init__(self):
        super(QualnameVisitor, self).__init__()
        self.stack = []
        self.qualnames = {}