142 class:
        control: sequence, if/else, loops, methods, parameters, returns
        input/output: scanner, files
        data: primitives, String, arrays, classes
143 class:
     control: recursion
     data: linked lists and binary trees
     --5 of 7 assessments just for those 3
     Java Collections Classes
     Arthur Riel's radio example:
         external view: client view, WHAT does it do?
         internal view: implementation view, HOW does it do it?
     ArrayList<E> -- we'll discuss ArrayIntList
     but another aspect of 143 is being a client of provided data structures