group

/*
 *  call-seq:
 *     thr.group   => thgrp or nil
 *  
 *  Returns the <code>ThreadGroup</code> which contains <i>thr</i>, or nil if
 *  the thread is not a member of any group.
 *     
 *     Thread.main.group   #=> #<ThreadGroup:0x4029d914>
 */

VALUE
rb_thread_group(thread)
    VALUE thread;
{
    VALUE group = rb_thread_check(thread)->thgroup;
    if (!group) {
        group = Qnil;
    }
    return group;
}