2 - YAPE::Regex::Explain

/(bb|[^b]{2})/ 

NODE                     EXPLANATION
----------------------------------------------------------------------
  (                        group and capture to \1:
----------------------------------------------------------------------
    bb                       'bb'
----------------------------------------------------------------------
   |                        OR
----------------------------------------------------------------------
    [^b]{2}                  any character except: 'b' (2 times)
----------------------------------------------------------------------
  )                        end of \1
----------------------------------------------------------------------