title: is a* the same as (a*)*?
body: <p>Quick question, 
  if <code>a</code> is a regular expression then is it true that <code>a* = (a*)*</code> ?</p>
  
  <p>Is <code>(a*)*</code> a valid expression? If it is, then can anyone explain why is it the same as <code>a*</code>? I apologize for asking here, but I couldn't find anything via Google.</p>