Empty creates an [iter.Seq] that yields nothing.

Gen creates an [iter.Seq] that yield number in range.

Once creates an [iter.Seq] that yields an element exactly once.

Repeat creates an [iter.Seq] that endlessly repeats a single element.

RepeatTimes creates an [iter.Seq] that repeats a single element a given number of times.

Variadic creates an [iter.Seq] from variadic elements.