def _setup_cmap(cmap, n_axes=1, norm=False):
    """Set color map interactivity."""
    if cmap == 'interactive':
        cmap = 'Reds' if norm else 'RdBu_r', True
    elif not isinstance(cmap, tuple):
        if cmap is None:
            cmap = 'Reds' if norm else 'RdBu_r'
        cmap = cmap, False if n_axes > 2 else True
    return cmap
