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. The tutorial is too long to upload to the Scratch site, so this is the first of three parts. The entire tutorial can be downloaded as one project from http://byob.berkeley.edu/BYOB3-Tutorial2.sb
