def METHOD_NAME(particle_types=['A'], dimensions=3, d=1, L=20):
    snap = two_particle_snapshot_factory()
    if snap.communicator.rank == 0:
        snap.constraints.N = 1
        snap.constraints.value[0] = 1.0
        snap.constraints.group[0] = [0, 1]
    return simulation_factory(snap)