code: private function renderLine()
      {
          $output = [];
          $output[] = $this->charCross;
          if (count($this->columns) > 0) {
              for ($columnNumber = 0; $columnNumber < count($this->columns); $columnNumber++) {
                  $output[] = $this->renderCell($columnNumber, $this->charHorizontal, $this->charHorizontal);
                  $output[] = $this->charCross;
              }
          }
          return implode('', $output);
      }
docs: Render line.
  
  @return string