code: def positions_to_contigs(positions):
      
  
      contig_labels = np.zeros_like(positions)
  
      contig_index = 0
      for i, p in enumerate(positions):
          if p == 0:
              contig_index += 1
          contig_labels[i] = contig_index
  
      return contig_labels
docs: Label contigs according to relative positions
  
      Given a list of positions, return an ordered list
      of labels reflecting where the positions array started
      over (and presumably a new contig began).
  
      Parameters
      ----------
      positions : list or array_like
          A piece-wise ordered list of integers representing
          positions
  
      Returns
      -------
      contig_labels : numpy.ndarray
          The list of contig labels