code: @Override
      public int getConnectedAtomsCount(IAtom atom) {
          int count = 0;
          for (int i = 0; i < bondCount; i++) {
              if (bonds[i].contains(atom)) ++count;
          }
          return count;
      }
docs: Returns the number of atoms connected to the given atom.
  
  @param  atom  The atom the number of bond partners are searched of.
  @return       The the size of connected atoms