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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 _context_source_file_url(path_or_url):
 """ Returns a URL for a remote or local context CSV file """

    if path_or_url.startswith('http'):
        # Remote CSV. Just return the URL
        return path_or_url

    if path_or_url.startswith('/'):
        # Absolute path
        return "file://" + path_or_url

    return "file://" + os.path.join(os.path.realpath(os.getcwd()), path_or_url)