code: public static Map<String, IAminoAcid> getHashMapBySingleCharCode() {
          IAminoAcid[] monomers = createAAs();
          HashMap<String, IAminoAcid> map = new HashMap<String, IAminoAcid>();
          for (int i = 0; i < monomers.length; i++) {
              map.put((String) monomers[i].getProperty(RESIDUE_NAME_SHORT), monomers[i]);
          }
          return map;
      }
docs: Returns a HashMap where the key is one of G, A, V, L, I, S, T, C, M, D,
  N, E, Q, R, K, H, F, Y, W and P.