kill-append

kill-append is a compiled Lisp function in `simple.el'.

(kill-append STRING BEFORE-P)

Append STRING to the end of the latest kill in the kill ring.
If BEFORE-P is non-nil, prepend STRING to the kill.
Also removes the last undo boundary in the current buffer,
depending on `kill-append-merge-undo'.
If `interprogram-cut-function' is set, pass the resulting kill to it.