Allow split string formula in Rules Engine

I've come across a scenario where I need to parse out values contained in a multipicklist and have discovered that I don't have a good way of doing this in the Rules Engine. I can do a LEFT substring and a RIGHT substring, but for any scenario where the value is A;B;C;D - I don't have a way to grab the B and C values. Can we please introduce a split string formula to take care of this use case?