function-get

function-get is a compiled Lisp function in `subr.el'.

(function-get F PROP &optional AUTOLOAD)

Return the value of property PROP of function F.
If AUTOLOAD is non-nil and F is autoloaded, try to autoload it
in the hope that it will set PROP. If AUTOLOAD is `macro', only do it
if it's an autoloaded macro.