def METHOD_NAME(mask_input, invert_mask=False):
    extrema = mask_input.getextrema()
    if (invert_mask):
        if extrema == (255,255): 
            print("after inverting mask will be blank. ignoring mask")  
            return None
    elif extrema == (0,0): 
        print("mask is blank. ignoring mask")  
        return None
    else:
        return mask_input    