zap-to-charNow that we have seen how search-forward and progn work,
we can see how the zap-to-char function works as a whole.
The first argument to kill-region is the position of the cursor
when the zap-to-char command is given—the value of point at
that time. Within the progn, the search function then moves
point to just after the zapped-to-character and point returns the
value of this location. The kill-region function puts together
these two values of point, the first one as the beginning of the region
and the second one as the end of the region, and removes the region.
The progn special form is necessary because the
kill-region command takes two arguments; and it would fail if
search-forward and point expressions were written in
sequence as two additional arguments. The progn expression is
a single argument to kill-region and returns the one value that
kill-region needs for its second argument.