This week's exercises will continue easing you into Rust and will feature some
components of object-oriented Rust that we're covering this week. You'll be
writing some programs that have more sophisticated logic that what you saw last
with last week's exercises. The first exercise is a warm-up: to implement the wc
command line utility in Rust. The second exercise is more challenging: to
implement the diff utility. In order to do so, you'll first find the longest
common subsequence (LCS) of lines between the two files and use this to inform
how you display your diff.