| instance methods | 
| add | thgrp.add( aThread )
        -> thgrp | 
 | Adds the given thread to this group, removing it from any other
      group to which it may have previously belonged. produces:| 
puts "Initial group is #{ThreadGroup::Default.list}"
tg = ThreadGroup.new
t1 = Thread.new { sleep 10 }
t2 = Thread.new { sleep 10 }
puts "t1 is #{t1}"
puts "t2 is #{t2}"
tg.add( t1 )
puts "Initial group now #{ThreadGroup::Default.list}"
puts "tg group now #{tg.list}"
 | 
 | 
Initial group is #<Thread:0x40196528>
t1 is #<Thread:0x4018d400>
t2 is #<Thread:0x4018d3c4>
Initial group now #<Thread:0x4018d3c4>#<Thread:0x40196528>
tg group now #<Thread:0x4018d400>
 | 
 | | list | thgrp.list
        -> anArray | 
 | Returns an array of all existing Threadobjects that belong 
      to this group.
  | ThreadGroup::Default.list | » | [#<Thread:0x40196528 run>] |  |