abbrev-modeabbrev-mode is an interactive compiled Lisp function in `
abbrev.el'. (abbrev-mode &optional ARG) Toggle Abbrev mode in the current buffer. With a prefix argument ARG, enable Abbrev mode if ARG is positive, and disable it otherwise. If called from Lisp, enable Abbrev mode if ARG is omitted or nil. In Abbrev mode, inserting an abbreviation causes it to expand and be replaced by its expansion.