def darken(color, amount=50):
    """ Makes a color darker by a variable amount """

    new_color = [0, 0, 0]
    for i in range(0, 3):
        if color[i] - amount > 0:
            new_color[i] = color[i] - amount
        else:
            new_color[i] = 0
    return tuple(new_color)