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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 get_url( width, height=None, background_color="cccccc", text_color="969696", text=None, random_background_color=False ):
 """ Craft the URL for a placeholder image. You can customize the background color, text color and text using the optional keyword arguments If you want to use a random color pass in random_background_color as True. """

    if random_background_color:
        background_color = _get_random_color()

    # If height is not provided, presume it is will be a square
    if not height:
        height = width
    d = dict(
        width=width,
        height=height,
        bcolor=background_color,
        tcolor=text_color
    )
    url = URL % d
    if text:
        text = text.replace(" ", "+")
        url = url + "?text=" + text
    return url