Example: web_concurrent_end

In the following example, the web_concurrent_end function marks the end of a concurrent group.

web_concurrent_start(NULL);
    web_add_header(...);
    web_url(..., "URL=http://...url1", ...);
    web_add_header(...);
    web_add_header(...);
    web_url(..., "URL=http://...url2", ...);
...
web_concurrent_end(NULL);