NullMomSampler Node1 NullMomSampler + ~NullMomSampler() + NullMomSampler() + shoot() Node2 MomSampler + m_val + MomSampler() + ~MomSampler() + shoot() Node2->Node1 Node3 ConstSampler + ConstSampler() + ConstSampler() + ~ConstSampler() + shoot() Node3->Node2 +m_mass Node4 Sampler + m_val + m_random + Sampler() + ~Sampler() + shoot() Node4->Node3