from collections import Counter
m = session.models[0]
ms = session.models[1]
counts = Counter(pb.atoms[0].residue.chain_id for pb in ms.pseudobonds)
print("# of missing segments:", len(ms.pseudobonds), counts)
for c in m.chains:
    print('Chain:', c.chain_id, len(c.residues), 'residues')
    print('  missing:', [i for i, r in enumerate(c.residues) if r is None])

