code: def atlas_zonefile_path( zonefile_dir, zonefile_hash ):
      
      # split into directories, but not too many
      zonefile_dir_parts = []
      interval = 2
      for i in xrange(0, min(len(zonefile_hash), 4), interval):
          zonefile_dir_parts.append( zonefile_hash[i:i+interval] )
  
      zonefile_path = os.path.join(zonefile_dir, '/'.join(zonefile_dir_parts), '{}.txt'.format(zonefile_hash))
      return zonefile_path
docs: Calculate the on-disk path to storing a zonefile's information, given the zone file hash.
      If the zonefile hash is abcdef1234567890, then the path will be $zonefile_dir/ab/cd/abcdef1234567890.txt
  
      Returns the path.