这报的是什么错啊？代码如下：

Question

>>> import networkx as nx
>>> G1=nx.DiGraph
>>> G1.add_edge(1,2)
Traceback (most recent call last):
File "<pyshell#2>", line 1, in <module>
G1.add_edge(1,2)
TypeError: unbound method add_edge() must be called with DiGraph instance as first argument (got int instance instead)

Answer 1

第二行改一下：G1=nx.DiGraph()

Answer 2

G1=nx.DiGraph()缺了（）