code: public function setTotalItems( $totalItems )
      {
          if (preg_match( '/^(?:\d*\.)?\d+$/', $totalItems ) !== 1) {
              throw new InvalidArgumentException( sprintf( 'Items total value should be a non-negative number (%s)',
                  $totalItems ) );
          }
  
          $this->totalItems = (float)number_format( $totalItems, 4, '.', '' );
  
          return $this;
      }
docs: @param  float $totalItems
  
  @return $this