title: Python 3 get all thread names in group
body: <p>I have code like this.
  And i need to get names of all threads in <em>test-grp</em> group.</p>
  
  <pre><code>t = threading.Thread(group='test-grp',name='test1',target=testFunc, args = (arg1,arg2))
  t.start()
  t2 = threading.Thread(group='test-grp',name='test2',target=testFunc, args = (arg1,arg2))
  t2.start()
  t3 = threading.Thread(group='test-grp',name='test3',target=testFunc, args = (arg1,arg2))
  t3.start()
  </code></pre>
  
  <p>It is possible to do what I want?</p>