let _button = document.getElementsByClassName('btn');
            _button[0].addEventListener('click', function(){
                let _input = document.getElementsByClassName('form-control');
                let _value = parseInt(_input[0].value);
                let _panel = document.getElementsByClassName('card');

                _panel[0].parentNode.appendChild(_panel[0].cloneNode(true));
                // let _html ='<div class="card border-info my-2">\
                //  <div class="card-body">\
                //      Panel content 1\
                //  </div>\
                // </div>';
                // _panel[0].parentNode.innerHTML = _panel[0].parentNode.innerHTML + _html;
                // _panel[0].parentNode.innerHTML += _html;

            });