import matplotlib.pyplot as plt
import numpy as np

# First create some toy data:
x = np.linspace(0, 2 * np.pi, 400)
y = np.sin(x**2)
z = np.cos(x**2)

# Create four polar Axes and access them through the returned array
fig, axsA = plt.subplots()
axsA.plot(x, y)
axsB = axsA.twinx()
axsB.plot(x, z)  # <-- Cannot access attribute "plot" for class "_AxesBase"