code: public function setFormatCode($pValue)
      {
          if ($pValue == '') {
              $pValue = self::FORMAT_GENERAL;
          }
          if ($this->isSupervisor) {
              $styleArray = $this->getStyleArray(['formatCode' => $pValue]);
              $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($styleArray);
          } else {
              $this->formatCode = $pValue;
              $this->builtInFormatCode = self::builtInFormatCodeIndex($pValue);
          }
  
          return $this;
      }
docs: Set Format Code.
  
  @param string $pValue see self::FORMAT_*
  
  @return NumberFormat