Produces an iterator over Item from a coroutine function that returns Generator<Item> and yields Items.

This is just a syntactic aid, as Generator<Item> is an iterator, so calling the generator function is what produces the iterator.

Example

auto generate_fibonacci = []() -> Generator<i32> {
  co_yield 0;
  i32 n1 = 0, n2 = 1;
  while (true) {
    i32 next = n1 + n2;
    n1 = n2;
    n2 = next;
    co_yield n1;
  }
};

// Directly using the generator iterator, in a for loop.
sus::Vec<i32> v;
for (i32 i : generate_fibonacci().take(7u)) {
  v.push(i);
}
sus_check(v == sus::Vec<i32>(0, 1, 1, 2, 3, 5, 8));

// Using `from_generator`, with collect.
sus::Vec<i32> v2 = generate_fibonacci().take(7u).collect_vec();
sus_check(v2 == sus::Vec<i32>(0, 1, 1, 2, 3, 5, 8));