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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 add_caption(self, image, caption, colour=None):
 """ Add a caption to the image """


        if colour is None:
            colour = "white"
    
        width, height = image.size
        draw = ImageDraw.Draw(image)

        draw.font = self.font

        draw.font = self.font
        draw.text((width // 10, height//20), caption,
                  fill=colour)

        return image