type pState struct {
	id     ProcID
	status go122.ProcStatus
	seq    seqCounter

	// rangeState is the state of special time ranges bound to this proc.
	rangeState
}

// mState is the state of a thread at a point in the trace.
type mState struct {
	g GoID   // Goroutine bound to this M. (The goroutine's state is Executing.)
	p ProcID // Proc bound to this M. (The proc's state is Executing.)