code: String getFormulasString() {
          StringBuilder sb = new StringBuilder();
          for (IMolecularFormula mf : getFormulas()) {
              if (sb.length() != 0)
                  sb.append(", ");
              sb.append(MolecularFormulaManipulator.getString(mf, false, true));
          }
          return sb.toString();
      }
docs: Pretty-print the MFs of this isotope container.
  @return the MFs