func randomTransition(ch *markovchain.Chain, state markovchain.State) markovchain.State {
entry := ch.Lookup(state)
if entry == nil || len(entry.Targets) == 0 {
return nil
}
prob := rand.Float64()
var curProb float64
for i, x := range entry.Probabilities {
curProb += x
if curProb > prob {
return entry.Targets[i]
}
}
return entry.Targets[len(entry.Targets)-1]
}
