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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_img_button(width=200, height=50, text='This is a button', color=rgb(200,100,50)):
 """ Draws a simple image button. """

    
    surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
    ctx = cairo.Context(surface)
    ctx.rectangle(0, 0, width - 1, height - 1)

    ctx.set_source_rgb(color.red/255.0, color.green/255.0, color.blue/255.0)
    ctx.fill()
    
    # Draw text
    ctx.set_source_rgb(1.0, 1.0, 1.0)
    ctx.select_font_face(
        "Helvetica",
        cairo.FONT_SLANT_NORMAL,
        cairo.FONT_WEIGHT_BOLD
    )
    ctx.set_font_size(15.0)
    ctx.move_to(15, 2 * height / 3)
    ctx.show_text(text)
    
    surface.write_to_png('button.png')