code: def find_pairs(self, tiles_34, first_index=0, second_index=33):
          
          pair_indices = []
          for x in range(first_index, second_index + 1):
              # ignore pon of honor tiles, because it can't be a part of pair
              if x in HONOR_INDICES and tiles_34[x] != 2:
                  continue
  
              if tiles_34[x] >= 2:
                  pair_indices.append(x)
  
          return pair_indices
docs: Find all possible pairs in the hand and return their indices
          :return: array of pair indices