Hreflang module for prestashop

GWT (Google webmaster tools) may give you some errors if you have a prestashop ecommerce site in different languages, infact, the GWT will not recognize the same pages in different languages, the result? a bunch of errors from duplicate content to hreflang links not present, and many others.
One solution is to have a hreflang module for prestashop a module that write the hreflang links in the head of your site.