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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 round_rectangle(size, radius, fill):
 """Draw a rounded rectangle"""

    width, height = size
    rectangle = Image.new('L', size, 255)  # fill
    corner = round_corner(radius, 255)  # fill
    rectangle.paste(corner, (0, 0))
    rectangle.paste(corner.rotate(90),
                    (0, height - radius))  # Rotate the corner and paste it
    rectangle.paste(corner.rotate(180), (width - radius, height - radius))
    rectangle.paste(corner.rotate(270), (width - radius, 0))
    return rectangle