anchor.diff:  library trainer;
  +
  +import 'dart:html';
  +import 'dart:convert';
   
   
   class Trainer{
  
positive.code:   Trainer(this.targettext);
    
    int get currentposition => _currentposition;
    void set currentposition(int n) => _currentposition = n;
    
    int currentposforward() => _currentposition++;
    
    int currentposbackward()=> _currentposition--;
    
    set errors(int n) => _errors = n;
    
  
negative.code:     return 100 - (_errors.toDouble() / sofar.length.toDouble() * 100).round();
  
    }
  }
  
  void initTrainer() {
    var target = querySelector('#targettext').text;
    var tr = new Trainer(target);
    var input = querySelector('#tarea');
    var output = querySelector('#test');
    input.onKeyUp.listen((e) {
          
          String typed = input.value.split('')[tr.currentposition];
      if (typed != tr.charAtPosition() ) {
        output.text = 'Error: ' + typed;
  
        tr.currentposforward();
      } else {
        tr.currentposforward();
      }
    });
  }