HTTP Re-Direct uri replace?

Wow, I completely misinterpreted string trimleft. I thought the chars variable was an integer of how many characters you wanted to trim from the left, but instead, it is a list of characters that you want to match, so it would be something like this:

set wininsert [string trimleft [HTTP::uri] /win]

This is very dangerous though since it could strip other parts of the URI away...I guess regsub string match is the best bet for this.