code: protected String getBondSymbol(IBond bond) {
          String bondSymbol = "";
          if (bond.getOrder() == IBond.Order.SINGLE) {
              if (isSP2Bond(bond)) {
                  bondSymbol = ":";
              } else {
                  bondSymbol = "-";
              }
          } else if (bond.getOrder() == IBond.Order.DOUBLE) {
              if (isSP2Bond(bond)) {
                  bondSymbol = ":";
              } else {
                  bondSymbol = "=";
              }
          } else if (bond.getOrder() == IBond.Order.TRIPLE) {
              bondSymbol = "#";
          } else if (bond.getOrder() == IBond.Order.QUADRUPLE) {
              bondSymbol = "*";
          }
          return bondSymbol;
      }
docs: Gets the bond Symbol attribute of the Fingerprinter class.
  
  @return       The bondSymbol value