code: public function getColumnMap()
      {
          $map = $this->getOption('column_map');
  
          if (null === $map) {
              $map = [];
              foreach ($this as $element) {
                  $col = $element->getOption('span');
                  if (null !== $col) {
                      $map[$element->getName()] = $col;
                  }
              }
  
              $this->setOption('column_map', $map);
          }
  
          return $map;
      }
docs: Gets the column map.
  
  Generates the column map from the element options,
  if none is set.
  
  @return array