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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 _make_pretty_usage(usage):
 """ Makes the usage description pretty and returns a formatted string if `usage` is not an empty string. Otherwise, returns None. """


    if usage is not None and usage.strip() != "":
        usage = "\n".join(map(lambda u: u.strip(), usage.split("\n")))
        return "%s\n\n" % usage