Variable: help-form
help-form is a variable defined in keyboard.c.
Value
nil
Documentation
Form to execute when character help-char is read.
If the form returns a string, that string is displayed.
If help-form is nil, the help char is not recognized.
Probably introduced at or before Emacs version 17.
Source Code
// Defined in /usr/src/emacs/src/keyboard.c
DEFVAR_LISP ("help-form", Vhelp_form,
doc: /* Form to execute when character `help-char' is read.
If the form returns a string, that string is displayed.
If `help-form' is nil, the help char is not recognized. */);