"Return version number of product as a string.
PRODUCT is a product structure which returned by `product-define'.
If optional argument UPDATE is non-nil, then regenerate
-`produce-version-string' from `product-version'."
+`product-version-string' from `product-version'."
(setq product (product-find product))
(or (product-version-string product)
(and (product-version product)