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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 download_url(url, back_off=True, **kwargs):
 """ Get the content of a URL and return a file-like object. back_off=True provides retry """

    if back_off:
        return _download_with_backoff(url, as_file=True, **kwargs)
    else:
        return _download_without_backoff(url, as_file=True, **kwargs)