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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 vars_args(parser):
 """Add various command line options for external vars"""

    parser.add_argument('--extra-vars',
                        dest='extra_vars',
                        help='Extra template variables',
                        default=[],
                        type=str,
                        action='append')
    parser.add_argument('--extra-vars-file',
                        dest='extra_vars_file',
                        help='YAML files full of variables',
                        default=[],
                        type=str,
                        action='append')