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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 active_version():
 """ Determine the current active version on the server Just examine the which environment is symlinked """

    
    link = '/'.join([deployment_root(),'env',env.project_name])
    if not exists(link): return None
    active = os.path.split(run('ls -al '+link).split(' -> ')[1])[1]
    return active