 www_open_url(+Url)Open URL in running version of the users’browser or start a new 
browser. This predicate tries the following steps:
www_open_url(+Url)Open URL in running version of the users’browser or start a new 
browser. This predicate tries the following steps:
- If a prolog flag (see set_prolog_flag/2) browseris set and this is the name of a known executable, use this. The flag 
may be set toCommand-Mode, where mode is one offgorbg, requesting Command to run in foreground or 
background mode. Default isbg.
- On Windows, use win_shell(open, URL)
- Find a generic‘open’comment. Candidates are xdg-open,openorgnome-open.
- If a environment variable BROWSERis set and this is 
the name of a known executable, use this.
- Try to find a known browser. @tbd Figure out the right tool in step 
3 as it is not uncommon that multiple are installed.