src/language-js/utils.js/isNgForOf
function isNgForOf(node, index, parentNode) {
  return (
    node.type === "NGMicrosyntaxKeyedExpression" &&
    node.key.name === "of" &&
    index === 1 &&
    parentNode.body[0].type === "NGMicrosyntaxLet" &&
    parentNode.body[0].value === null
  );
}