text: import {Context, ContextTypes} from "./node"
  import Expression from "./expression"
  export default class Yield extends Expression {
      /** @type {?Expression} */
      get value() {
          return this.cacheNode("value")
      }
      /** @type {?Expression} */
      get key() {
          return this.cacheNode("key")
      }
      // FIXME
  }
  