def CalculateNumBonds(mol):
    """
    Calculation the number of bonds where between heavy atoms       
    --->nBond
        
    :param mol: molecule
    :type mol: rdkit.Chem.rdchem.Mol
    :return: the number of bonds where between heavy atoms
    :rtype: int
    
    """
    nBond = mol.GetNumBonds()    
    return nBond