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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 update(env):
 """ Update an existing cipr project to the latest intalled version. """

    files = [path.join(env.project_directory, 'cipr.lua')]
    for filename in files:
        if path.exists(filename):
            os.remove(filename)
    app.command.run(['init', env.project_directory])