code: function internalIIAFE(body) {
          return {
              type: 'AwaitExpression',
              argument: asyncDefine({
                  "type": "FunctionExpression",
                  "generator": false,
                  "expression": false,
                  "async": true,
                  "params": [],
                  "body": {
                      "type": "BlockStatement",
                      "body": body
                  }
              }).body.body[0].argument
          };
      }
docs: /* Generate an expression AST the immediate invokes the specified async function, e.g.
  (await ((async function(){ ...body... })()))