I know I told you to change this to use indexing, but the code still has to clear about what it's doing and why. It's clear enough that the 11 refers to the length of "instructor_" (although a comment mentioning that would be helpful), but what does 6 refer to here? Comments are helpful.

Also, you're repeating the code that replaces `/` with `.`, as well as the lowercasing. Can those be pulled out of the `if` block, and done once outside of it?