How to use the @nuxt/utils.createRoutes function in @nuxt/utils

srcDir: this.template.dir + '/pages',
        routeNameSplitter,
        trailingSlash
      })
    } else if (this._nuxtPages) {
      // Use nuxt.js createRoutes bases on pages/
      const files = {}
      const ext = new RegExp(`\\.(${this.supportedExtensions.join('|')})$`)
      for (const page of await this.resolveFiles(this.options.dir.pages)) {
        const key = page.replace(ext, '')
        // .vue file takes precedence over other extensions
        if (/\.vue$/.test(page) || !files[key]) {
          files[key] = page.replace(/(['"])/g, '\\$1')
        }
      }
      templateVars.router.routes = createRoutes({
        files: Object.values(files),
        srcDir: this.options.srcDir,
        pagesDir: this.options.dir.pages,
        routeNameSplitter,
        supportedExtensions: this.supportedExtensions,
        trailingSlash
      })
    } else { // If user defined a custom method to create routes
      templateVars.router.routes = await this.options.build.createRoutes(
        this.options.srcDir
      )
    }

    await this.nuxt.callHook(
      'build:extendRoutes',
      templateVars.router.routes,

async resolveRoutes ({ templateVars }) {
    consola.debug('Generating routes...')
    const { routeNameSplitter, trailingSlash } = this.options.router

    if (this._defaultPage) {
      templateVars.router.routes = createRoutes({
        files: ['index.vue'],
        srcDir: this.template.dir + '/pages',
        routeNameSplitter,
        trailingSlash
      })
    } else if (this._nuxtPages) {
      // Use nuxt.js createRoutes bases on pages/
      const files = {}
      const ext = new RegExp(`\\.(${this.supportedExtensions.join('|')})$`)
      for (const page of await this.resolveFiles(this.options.dir.pages)) {
        const key = page.replace(ext, '')
        // .vue file takes precedence over other extensions
        if (/\.vue$/.test(page) || !files[key]) {
          files[key] = page.replace(/(['"])/g, '\\$1')
        }
      }