zap-to-char function changed little between GNU Emacs
version 19 and GNU Emacs version 22. However,
calls another function,
kill-region, which enjoyed a major
kill-region function in Emacs 19 is complex, but does not
use code that is important at this time. We will skip it.
kill-region function in Emacs 22 is easier to read than the
same function in Emacs 19 and introduces a very important concept,
that of error handling. We will walk through the function.
But first, let us look at the interactive