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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 clean_url(url):
 """URL Validation function"""

        if not url.startswith(('http://', 'https://')):
            url = f'http://{url}'

        if not URL_RE.match(url):
            raise BadURLException(f'{url} is not valid')

        return url