code: private static boolean hasCommonAtom(IBond bondA, IBond bondB) {
          return bondA.contains(bondB.getBegin()) || bondA.contains(bondB.getEnd());
      }
docs: Determines if two bonds have at least one atom in common.
  
  @param  atom  first bondA1
  @param  bondB  second bondA1
  @return    the symbol of the common atom or "" if
  the 2 bonds have no common atom