Subplots with QuTip Bloch sphere: render() got an unexpected keyword argument 'fig'

Question

I want to subplot the Bloch sphere.

from mpl_toolkits.mplot3d import Axes3D
fig, ax = plt.subplots(figsize=(7, 7), subplot_kw=dict(projection='3d'))
b = qt.Bloch(fig=fig, axes=ax)
b = qt.Bloch(fig=fig, axes=ax)
--->b.render(fig=fig, axes=ax)
plt.show()

TypeError: render() got an unexpected keyword argument 'fig'

According to the sourcecode of qutip.bloch:

 def render(self, fig=None, axes=None):
        """
        Render the Bloch sphere and its data sets in on given figure and axes.
        """

The render() got keyword argument 'fig'. (https://qutip.org/docs/4.0.2/modules/qutip/bloch.html)

Can someone help me? Thanks!