Canonical

import bagel as bg

residues = [bg.Residue(name='A', chain_ID='A', index=i, mutable=True) for i in range(6)]
state = bg.State(name='state_A', chains=[bg.Chain(residues)], energy_terms=[])
system = bg.System(states=[state])

mutator = bg.mutation.Canonical(n_mutations=1)
mutated_system, mutation_record = mutator.one_step(system)