Closure iterators not using a generator require passing in the state, when you
pass in `1, 2` it finishes the iterator since it already iterated to `2`.
The 'proper' way of doing what you want is to write a closure generator that
stores the state on instantiation:
proc makeMyClos(a, b: int): iterator: int =
result = iterator: int {.closure.} =
for x in a..b:
yield x
proc f(it: iterator) =
echo it()
echo it()
echo it()
echo it()
f(makeMyClos(1, 4))
Run
This stores the creation state with the iterator so one does not need to pass
the data and is a more understandable construct. Not that there is no use case
for a normal iterator. (My Package Slicerator contains a
[asClosure](https://github.com/beef331/slicerator/blob/master/src/closures.nim#L60-L62)
macro that handles this automatically
