docs: def _add_generate_sub_commands(self):
          """
          Sub commands for generating models for usage by clients.
          Currently supports Google Closure.
          """
  
          gen_parser = self._subparsers_handle.add_parser(
              name="gen",
              help="generate client side model stubs, filters"
              )
  
          gen_parser.add_argument(
              "-t",
              "--template",
              choices=['closure.model', 'closure.filter'],
              default='closure.model',
              required=True,
              dest="template",
              help="template to use for client side code generation"
              )
  
          gen_parser.add_argument(
              "-m",
              "--model",
              required=True,
              dest="models_definition",
              help="path to models definition file or package"
              )
  
          gen_parser.add_argument(
              "-o",
              "--output",
              default=".",
              dest="output",
              help="output path for generated code"
              )
  
          gen_parser.add_argument(
              "-n",
              "--namespace",
              required=True,
              dest="namespace",
              help="namespace to use with template e.g prestans.data.model"
              )
  
          gen_parser.add_argument(
              "-fn",
              "--filter-namespace",
              required=False,
              default=None,
              dest="filter_namespace",
              help="filter namespace to use with template e.g prestans.data.filter"
              )