def add_letter_to_axis(ax, let, col, x, y, height):
    """Add 'let' with position x,y and height height to matplotlib axis 'ax'.
    """
    from shapely import affinity
    from descartes.patch import PolygonPatch
    if len(let) == 2:
        colors = [col, 'white']
    elif len(let) == 1:
        colors = [col]
    else:
        raise ValueError('3 or more Polygons are not supported')
    for polygon, color in zip(let, colors):
        new_polygon = affinity.scale(polygon, yfact=height, origin=(0, 0, 0))
        new_polygon = affinity.translate(new_polygon, xoff=x, yoff=y)
        patch = PolygonPatch(new_polygon, edgecolor=color, facecolor=color)
        ax.add_patch(patch)
    return
