Over the next few lectures we're going to advance study intermediate student
language and learn a new language construct called the local expression.
What local expressions let us do is to have definitions, functions and
constants, that are only available within one small part of the program.
Once we learn how local works, which we'll do over three short videos, then
we're going to look at two important ways to use local.
One has to do with organizing programs that are large or written by more than
one person. Another has to do with dealing with
important performance problems when we can't use local.