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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_container_version():
 """Return the version of the docker container running the present server, or '' if not in a container"""

    root_dir = os.path.dirname(os.path.realpath(sys.argv[0]))
    version_file = os.path.join(root_dir, 'VERSION')
    if os.path.exists(version_file):
        with open(version_file) as f:
            return f.read()
    return ''