[REBOL] [REBOL] Indexing strings

[tim]

Looking at strings documentation... but I can't find
what I'm looking for.

Given a character, would like to get a matching index
in string. (If there is a match).
For example:

ch: "b"
str: "abc"

How do I get the location of "b" in "abc"?

Also, am testing. Nothing from Rebol list for several days.
Thanks Tim