Example: web.concurrent_start

In the following example, the concurrent_start function marks the beginning of a concurrent group.

web.concurrent_start(null);
     web.add_header(...);
     web.url(..., "URL=http://...url1", new String[]{ ...);
     web.add_header(...);
     web.add_header(...);
     web.url(..., "URL=http://...url2", new String[]{ ...);
web.concurrent_end(null);