code: function (element) {
  
        var id = element.getAttribute('id'),
            formula = element.getAttribute('data-formula');
  
        if (formula) {
          // add item with basic properties to data array
          instance.matrix.addItem({
            id: id,
            formula: formula
          });
  
          calculateElementFormula(formula, element);
        }
  
      }
docs: register new found element to matrix
  @param {Element} element
  @returns {Object}