This is the second BYOB3 tutorial, about the use of higher order functions (functions with functions as inputs) to manipulate list data: MAP, KEEP, and COMBINE. This project runs in Scratch 1.4, but the functions described herein run only in BYOB. The first tutorial can be found at http://byob.berkeley.edu or on the Scratch site at http://scratch.mit.edu/projects/bharvey/1011223 for the first half. This tutorial is too big to upload to the Scratch web site, so it's in three parts; this is part B. Part A can be found at http://scratch.mit.edu/projects/bharvey/1021750 or the whole thing in one project is at http://byob.berkeley.edu/BYOB3-Tutorial2.sb
