code: func (a *Automaton) initTransition(state int, t *Transition) int {
  	assert2(state < a.numStates(), "state=%v nextState=%v", state, a.numStates())
  	t.source = state
  	t.transitionUpto = a.states[2*state]
  	return a.numTransitions(state)
  }
docs: /*
  Initialize the provided Transition to iterate through all transitions
  leaving the specified state. You must call nextTransition() to get
  each transition. Returns the number of transitions leaving this tate.
  */