code: func New(opts ...ConsOpt) *Tagger {
  	p := &Tagger{
  		Output: make(chan lingo.AnnotatedSentence),
  
  		sentences: make(chan lingo.AnnotatedSentence),
  	}
  
  	for _, opt := range opts {
  		opt(p)
  	}
  
  	if p.Model == nil {
  		p.Model = &Model{perceptron: newPerceptron()}
  		p.cachedTags = make(map[string]lingo.POSTag)
  	}
  
  	return p
  }
docs: // New creates a new *Tagger