tree

import networkx as nx

g = nx.DiGraph()
g.add_node(0, value=1, id=0)
g.add_node(1, value=2, id=1)
g.add_node(2, id=2)
g.add_edge(0, 1)
g.add_edge(0, 2)
g.nodes[0]

{'value': 1, 'id': 0}