text: import Vue from './instance/index' // 这个是核心入口
  import { initGlobalAPI } from './global-api/index'
  import { isServerRendering } from 'core/util/env'
  import { FunctionalRenderContext } from 'core/vdom/create-functional-component'
  
  // 暴露api入口
  initGlobalAPI(Vue)
  
  Object.defineProperty(Vue.prototype, '$isServer', {
    get: isServerRendering
  })
  
  Object.defineProperty(Vue.prototype, '$ssrContext', {
    get () {
      /* istanbul ignore next */
      return this.$vnode && this.$vnode.ssrContext
    }
  })
  
  // expose FunctionalRenderContext for ssr runtime helper installation
  Object.defineProperty(Vue, 'FunctionalRenderContext', {
    value: FunctionalRenderContext
  })
  
  Vue.version = '__VERSION__'
  
  export default Vue
  