custom-initialize-defaultcustom-initialize-default is a compiled Lisp function in `
custom.el'. (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 symbol.