code: func repeatMin(a *Automaton, min int) *Automaton {
  	if min == 0 {
  		return repeat(a)
  	}
  	as := make([]*Automaton, 0, min+1)
  	for min > 0 {
  		as = append(as, a)
  		min--
  	}
  	as = append(as, repeat(a))
  	return concatenateN(as)
  }
docs: /*
  Returns an automaton that accepts min or more concatenated
  repetitions of the language of the given automaton.
  
  Complexity: linear in number of states and in min.
  */