import networkx as nx
import matplotlib.pyplot as plt

def main():
    # Tree
    G = nx.DiGraph()
    G.add_node("A")
    G.add_node("B")
    G.add_node("C")
    G.add_edge("A", "B")
    G.add_edge("B", "C")
    print(G.nodes())
    print(G.edges())
    print(G.degree())

    nx.draw(G, with_labels=True)
    plt.show()

if __name__ == "__main__":
    main()