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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def draw_mask(im, mask, alpha=0.5, color=None):
 """ Overlay a mask on top of the image. Args: im: a 3-channel uint8 image in BGR mask: a binary 1-channel image of the same size color: if None, will choose automatically """

    if color is None:
        color = PALETTE_RGB[np.random.choice(len(PALETTE_RGB))][::-1]
    im = np.where(np.repeat((mask > 0)[:, :, None], 3, axis=2),
                  im * (1 - alpha) + color * alpha, im)
    im = im.astype('uint8')
    return im