code: function initRoutes (ravelInstance, koaRouter) {
    const proto = Object.getPrototypeOf(this);
    // handle class-level @mapping decorators
    const classMeta = Metadata.getClassMeta(proto, '@mapping', Object.create(null));
    for (const r of Object.keys(classMeta)) {
      buildRoute(ravelInstance, this, koaRouter, r, classMeta[r]);
    }
  
    // handle methods decorated with @mapping
    const meta = Metadata.getMeta(proto).method;
    const annotatedMethods = Object.keys(meta);
    for (const r of annotatedMethods) {
      const methodMeta = Metadata.getMethodMetaValue(proto, r, '@mapping', 'info');
      if (methodMeta) {
        buildRoute(ravelInstance, this, koaRouter, r, methodMeta);
      }
    }
  }
docs: Initializer for this `Routes` class.
  
  @param {Ravel} ravelInstance - Instance of a Ravel app.
  @param {Object} koaRouter - Instance of koa-router.
  @private