old_contents: 
  def burrows_wheeler(text):
      """Returns the burrows wheeler transform of <text>.
  
      The text is assumed to not contain the character $"""
  
      text += "$"
      all_permutations = []
      for i in range(len(text)):
          all_permutations.append(text[i:] + text[:i])
  
      all_permutations.sort()
      return "".join([w[-1] for w in all_permutations])
  
new_contents: 
  def burrows_wheeler(text):
      """Calculates the burrows wheeler transform of <text>.
  
      returns the burrows wheeler string and the suffix array indices
      The text is assumed to not contain the character $"""
  
      text += "$"
      all_permutations = []
      for i in range(len(text)):
          all_permutations.append((text[i:] + text[:i],i))
  
      all_permutations.sort()
      bw_l = [] # burrows wheeler as list
      sa_i = [] # suffix array indices
  
      for w,j in all_permutations:
          bw_l.append(w[-1])
          sa_i.append(j)
  
      return "".join(bw_l), sa_i
  
subject: Return suffix array indices from burrows wheeler