base.flows.ActorImplMut[S:imm,mut,read,E:imm,mut,read,R:imm,mut,read]

read #(downstream: mutH base.flows._ActorSink[R], state: mutH S, e: E): imm base.flows.ActorRes,
read #(downstream: mutH base.flows._ActorSink[R], state: mutH S, e: E): imm base.flows.ActorRes,