code: function isLet(node, parent) {
    if (!t.isVariableDeclaration(node)) return false;
    if (node._let) return true;
    if (node.kind !== "let") return false;
  
    // https://github.com/babel/babel/issues/255
    if (isLetInitable(node, parent)) {
      for (var i = 0; i < node.declarations.length; i++) {
        var declar = node.declarations[i];
        declar.init = declar.init || t.identifier("undefined");
      }
    }
  
    node._let = true;
    node.kind = "var";
    return true;
  }
docs: [Please add a description.]