Is your feature request related to a problem? Please describe.
Implementation of the slice selector [<start>:<end>:<step>] for positive steps and positive bounds.

Describe the solution you'd like
Slice for positive steps should be similar to the regular index selector. There are no extraordinary challenges, storing the current index as part of the state should suffice (we already do this for index selectors), and the output is in regular order.

Additional context
RFC draft