docs: def cycle_find(key, width=4):
      """
      Given an element of a de Bruijn sequence, find its index in that sequence.
  
      Args:
          key(str): The piece of the de Bruijn sequence to find.
          width(int): The width of each element in the sequence.
  
      Returns:
          int: The index of ``key`` in the de Bruijn sequence.
      """
  
      key_len = len(key)
      buf = ''
  
      it = deBruijn(width, 26)
  
      for i in range(key_len):
          buf += chr(ord('A') + next(it))
  
      if buf == key:
          return 0
  
      for i, c in enumerate(it):
          buf = buf[1:] + chr(ord('A') + c)
          if buf == key:
              return i + 1
  
      return -1