/// <summary>
 /// Calculates the total number of hydrogens (implicit and explicit)
 /// </summary>
 /// <param name="atom"></param>
 /// <returns></returns>
 public static uint TotalNumHydrogens(this OBAtom atom)
 {
     return(atom.ImplicitHydrogenCount() + atom.ExplicitHydrogenCount());
 }