Identify the error in this code snippet for plotting a 3D bar chart:

Identify the error in this code snippet for plotting a 3D bar chart:

import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
fig = plt.figure()
ax = fig.add_subplot(111)
x = [1, 2]
y = [3, 4]
z = [0, 0]
dx = dy = 1
dz = [5, 6]
ax.bar3d(x, y, z, dx, dy, dz)
plt.show()