How to use the lwc.registerTemplate function in lwc

function tmpl($api, $cmp, $slotset, $ctx) {
  const { h: api_element } = $api;
  return [
    api_element(
      "section",
      {
        style: $cmp.customStyle,
        key: 2
      },
      []
    )
  ];
}

export default registerTemplate(tmpl);
tmpl.stylesheets = [];

),
    api_element(
      "audio",
      {
        attrs: {
          src: "http://www.example.com/video.mp3",
          crossorigin: "anonymous"
        },
        key: 2
      },
      []
    )
  ];
}

export default registerTemplate(tmpl);
tmpl.stylesheets = [];

[api_text("2")]
        )
      : null,
    $cmp.isTrue
      ? api_element(
          "p",
          {
            key: 2
          },
          [api_text("3")]
        )
      : null
  ];
}

export default registerTemplate(tmpl);
tmpl.stylesheets = [];

api_element(
              "p",
              {
                key: 6
              },
              [api_text("Default footer")]
            )
          ],
          $slotset
        )
      ]
    )
  ];
}

export default registerTemplate(tmpl);
tmpl.slots = ["header", "", "footer"];
tmpl.stylesheets = [];

return [
    api_element(
      "section",
      {
        key: 0
      },
      [
        $cmp.state.isTrue ? api_dynamic($cmp.foo) : null,
        $cmp.state.isTrue ? api_text(" ") : null,
        $cmp.state.isTrue ? api_dynamic($cmp.bar) : null
      ]
    )
  ];
}

export default registerTemplate(tmpl);
tmpl.stylesheets = [];

import { registerTemplate, registerComponent, LightningElement, registerDecorators } from 'lwc';

function tmpl($api, $cmp, $slotset, $ctx) {
    const {
        t: api_text
    } = $api;
    return [api_text("ts test")];
}

var _tmpl = registerTemplate(tmpl);
tmpl.stylesheets = [];
tmpl.stylesheetTokens = {
    hostAttribute: "x-typescript_typescript-host",
    shadowAttribute: "x-typescript_typescript"
};
const Test = 1;
class ClassAndTemplate extends LightningElement {
    constructor() {
        super();
        this.t = Test;
        this.counter = 0;
    }
}
registerDecorators(ClassAndTemplate, {
    fields: ["t"]
});

"p",
          {
            attrs: {
              "data-foo": "1",
              "data-bar-baz": "xyz"
            },
            key: 0
          },
          []
        )
      ]
    )
  ];
}

export default registerTemplate(tmpl);
tmpl.stylesheets = [];

attrs: {
              x1: line.x1,
              y1: line.y1,
              x2: line.x2,
              y2: line.y2
            },
            key: api_key(0, line.key)
          },
          []
        );
      })
    )
  ];
}

export default registerTemplate(tmpl);
tmpl.stylesheets = [];

key: 1
      },
      [
        api_element(
          "p",
          {
            key: 0
          },
          [api_dynamic($cmp.obj.sub)]
        )
      ]
    )
  ];
}

export default registerTemplate(tmpl);
tmpl.stylesheets = [];

import { registerTemplate } from "lwc";
import stylesheet0 from "@shared/styles";
import stylesheet1 from "./local";

function tmpl($api, $cmp, $slotset, $ctx) {
  const {} = $api;
  return [];
}

export default registerTemplate(tmpl);
const stylesheets = [stylesheet0, stylesheet1];
tmpl.stylesheets = stylesheets;