choose-completion-string

choose-completion-string is a compiled Lisp function in `simple.el'.

(choose-completion-string CHOICE &optional BUFFER BASE-POSITION INSERT-FUNCTION)

Switch to BUFFER and insert the completion choice CHOICE.
BASE-POSITION says where to insert the completion.
INSERT-FUNCTION says how to insert the completion and falls
back on `completion-list-insert-choice-function' when nil.