import matplotlib.pyplot as plt

plt.figure(1, figsize=(3,3))
ax = plt.subplot(111)

ax.annotate("",
            xy=(0.2, 0.2), xycoords='data',
            xytext=(0.8, 0.8), textcoords='data',
            arrowprops=dict(arrowstyle="->",
                            connectionstyle="arc3"), 
            )

plt.show()