code: private static DNAStrand getOrCreateStrand(HashMap<Integer, DNAStrand> strands, int color) {
          DNAStrand strand = strands.get(color);
          if (strand == null) {
              strand = new DNAStrand();
              strand.color = color;
              strand.count = 0;
              strands.put(strand.color, strand);
          }
          return strand;
      }
docs: Try to get a strand of the given color. Create it if it doesn't exist.