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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_system_cert_file():
 """Try to find a system-wide SSL certificate file. @return: the filename to the cert file @raises: ValueError when no system cert file could be found """

    if os.name == 'posix':
        filename = "/etc/ssl/certs/ca-certificates.crt"
        if os.path.isfile(filename):
            return filename
    msg = "no system certificate file found"
    raise ValueError(msg)