def stack_colormap(lower, upper, n=<NUM_LIT>):
A = get_cmap(lower)<EOL>B = get_cmap(upper)<EOL>name = "<STR_LIT>" % (A.name, B.name)<EOL>lin = np.linspace(<NUM_LIT:0>, <NUM_LIT:1>, n)<EOL>return array_cmap(np.vstack((A(lin), B(lin))), name, n=n)<EOL>
Stacks two colormaps (``lower`` and ``upper``) such that
low half -> ``lower`` colors, high half -> ``upper`` colors

Args:

    lower (colormap): colormap for the lower half of the stacked colormap.

    upper (colormap): colormap for the upper half of the stacked colormap.

    n (int): Number of colormap steps. Default is ``256``.