custom-initialize-defaultcustom-initialize-default is a compiled Lisp function in `
(custom-initialize-default SYMBOL EXP)
Initialize SYMBOL with EXP.
This will do nothing if symbol already has a default binding.
Otherwise, if symbol has a `saved-value' property, it will evaluate
the car of that and use it as the default binding for symbol.
Otherwise, EXP will be evaluated and used as the default binding for