code: def is_list(node):
      
      return (isinstance(node, Node)
              and len(node.children) > 1
              and isinstance(node.children[0], Leaf)
              and isinstance(node.children[-1], Leaf)
              and node.children[0].value == u"["
              and node.children[-1].value == u"]")
docs: Does the node represent a list literal?