find-cmpl-prefix-entry
find-cmpl-prefix-entry is a compiled Lisp function in `completion.el
'.
(find-cmpl-prefix-entry PREFIX-STRING)
Return the prefix entry for string.
Sets `cmpl-db-prefix-symbol'.
Prefix-string must be exactly `completion-prefix-min-length' long
and downcased. Sets up `cmpl-db-prefix-symbol'.