Is this valid or invalid ES6?

valid-or-invalid.es6

function * append (...iterables) {
  for (const iterable of iterables) {
    yield * iterable;
  }
}

const lyrics = append(["a", "b", "c"], ["one", "two", "three"], ["do", "re", "me"]);

for (const word of lyrics) {
  console.log(word);
}
  //=>
    a
    b
    c
    one
    two
    three
    do
    re
    me

@raganwald, I agree with @nikitadyumin, the only issue here is const. Runs fine on Edge (with full generator support) when const becomes let.