code: public static int getTriplet(NucleotideSequence nSequence, int tripletStart) {
          int triplet = (nSequence.codeAt(tripletStart) << 4) |
                  (nSequence.codeAt(tripletStart + 1) << 2) |
                  nSequence.codeAt(tripletStart + 2);
          return triplet;
      }
docs: Extracts {@literal int} representation of triplet starting from specified position (see implementation for
  details).
  
  @param nSequence    nucleotide sequence
  @param tripletStart position of first nucleotide of triplet
  @return {@literal int} representation of triplet