code: @Override
      public int getConnectedSingleElectronsCount(IAtom atom) {
          int count = 0;
          for (int i = 0; i < singleElectronCount; i++) {
              if (singleElectrons[i].contains(atom)) ++count;
          }
          return count;
      }
docs: Returns the sum of the SingleElectron for a given Atom.
  
  @param  atom  The atom on which the single electron is located
  @return       The array of SingleElectron of this AtomContainer