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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 package_version():
 """ Determine the version of this package. :return: String representing known version """

    version = ""
    try:
        version = pkg_resources.get_distribution('instana').version
    except pkg_resources.DistributionNotFound:
        version = 'unknown'
    finally:
        return version