text: function insert(num){
    const number = document.getElementById('visor').innerHTML;
    document.getElementById('visor').innerHTML = number + num
  }
  
  function cleanVisor(){
    document.getElementById('visor').innerHTML = ''
  }
  
  function result(){
    var visor = document.getElementById('visor').innerHTML;
    if(visor){
      document.getElementById('visor').innerHTML =eval(visor)
    }else{
      document.getElementById('visor').innerHTML = ''
    }
  }