如何从函数返回matplotlib图形？

import matplotlib.pyplot as plt

def plot_graph():
    x = [1, 2, 3, 4, 5]
    y = [2, 4, 6, 8, 10]
    plt.plot(x, y)

def plot_graph():
    x = [1, 2, 3, 4, 5]
    y = [2, 4, 6, 8, 10]
    plt.plot(x, y)
    plt.show()

def plot_graph():
    x = [1, 2, 3, 4, 5]
    y = [2, 4, 6, 8, 10]
    plt.plot(x, y)
    return plt.gcf()

graph = plot_graph()