Stream.iterate
You're seeing just the function
iterate, go back to Stream module for more information.
Specs
iterate(element(), (element() -> element())) :: Enumerable.t()
Emits a sequence of values, starting with start_value. Successive
values are generated by calling next_fun on the previous value.
Examples
iex> Stream.iterate(0, &(&1 + 1)) |> Enum.take(5)
[0, 1, 2, 3, 4]