code: func (sm *StateMachine) SetStates(ssss ...[][]State) {
  	for i, sss := range ssss {
  		for j, ss := range sss {
  			for k, s := range ss {
  				sm.Handlers = append(sm.Handlers, s)
  				if len(s.Label) > 0 {
  					sm.states[s.Label] = i + j + k
  				}
  			}
  		}
  	}
  }
docs: // SetStates takes [][]State as an argument. Note that it's a slice of a slice,
  // which is used to enable tasks like requesting a user's shipping address,
  // which themselves are []Slice, to be included inline when defining the states
  // of a stateMachine.