from spb.backends.matplotlib import MB
import colorcet as cc
class MBchild(MB):
    colormaps = ["plotly3", cc.bmy]
plot3d(
    (cos(x**2 + y**2), (x, -2, 0), (y, -2, 2)),
    (cos(x**2 + y**2), (x, 0, 2), (y, -2, 2)),
    backend=MBchild, n1=25, n2=50, use_cm=True)