Iterable integers

Iterable integers actually make sense if you are comfortable with throwing away some readability

`
for i in 100:
    print(i)
`
this would be equivalent to 

`
for i in range(100):
    print(i)
`
Maybe introduce an alternate keyword `under` or `below` like

`
for i under 100:
    print(i)
`

Negative numbers could slightly change the behavior to

`for i in range(0,-100,-1)`
