m{
      (?(DEFINE)
         (?<x>
            ( . ) ( . )
            (?{ '...' })
         )
         (?<y>
            (?<y1> . ) (?<y2> . )
            (?{ print("($+{y1},$+{y2})") })
         )
         (?<z>
            ( . ) ( . )
            (?{ '...' })
         )
      )

      (?&y)+
   }x;