import IMP.atom
m= IMP.Model()
prot= IMP.atom.read_pdb(IMP.atom.get_example_path("example_protein.pdb"), m)
bds= IMP.atom.get_internal_bonds(prot)
bl= IMP.container.ListSingletonContainer(bds.get_particles())
h= IMP.core.Harmonic(0,1)
bs= IMP.atom.BondSingletonScore(h)
br= IMP.container.SingletonsRestraint(bs, bl)
m.add_restraint(br)
print m.evaluate(False)