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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_python_version_string():
 """ Returns a string representation of the Python version. :return: "2.7.8" if python version is 2.7.8. :rtype string """

    version_info = sys.version_info
    return '.'.join(map(str, [version_info[0], version_info[1], version_info[2]]))