def update_args(ctx, instance, branch, commit, locals_path, requirements,
        setup_environment):
    # Do the sanity checks.
    instance = cset("instance", instance)
    if not instance or not instance.isalnum():
        abort("You have to specify a proper alphanumeric instance name!")
    if branch is not None and commit is not None:
        abort("You can only deploy specific commit OR specific branch")
    commit and cset("commit", commit, force=True)
    branch and cset("branch", branch, force=True)
    cset("locals_path", locals_path)
    cset("requirements", get_boolean(requirements))
    cset("setup_environment", get_boolean(setup_environment))
    return ctx
Check args and update ctx.
dataset/ETHPy150Open ipeirotis/Mturk-Tracker/deployment/fabfile.py/update_args