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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 user_agent_info(sdk_version, custom_user_agent):
 # type: (str, str) -> str """Return the user agent info along with the SDK and Python Version information. :param sdk_version: Version of the SDK being used. :type sdk_version: str :param custom_user_agent: Custom User Agent string provided by the developer. :type custom_user_agent: str :return: User Agent Info string :rtype: str """

    python_version = ".".join(str(x) for x in sys.version_info[0:3])
    user_agent = "ask-python/{} Python/{}".format(
        sdk_version, python_version)
    if custom_user_agent is None:
        return user_agent
    else:
        return user_agent + " {}".format(custom_user_agent)