def add_swagger_api_route(app, target_route, swagger_json_route):
    """
    mount a swagger statics page.
    app: the sanic app object
    target_route: the path to mount the statics page.
    swagger_json_route: the path where the swagger json definitions is
                        expected to be.
    """
    static_root = get_swagger_static_root()
    swagger_body = generate_swagger_html(
        STATIC_ROOT, swagger_json_route
    ).encode("utf-8")

    async def swagger_ui(request):
        return HTTPResponse(body_bytes=swagger_body, content_type="text/html")

    bp = Blueprint('swagger')
    bp.static(STATIC_ROOT, static_root)

    app.add_route(swagger_ui, target_route, methods=["GET"])
    app.blueprint(bp)
mount a swagger statics page.
    app: the sanic app object
    target_route: the path to mount the statics page.
    swagger_json_route: the path where the swagger json definitions is
                        expected to be.