code: public function setBin( $bin )
      {
          $bin = trim( $bin );
  
          if (strlen( $bin ) !== 6) {
              throw new InvalidArgumentException( sprintf( 'Bin number should contain the first 6 characters in the card number (%s)',
                  $bin ) );
          }
  
          $this->bin = $bin;
  
          return $this;
      }
docs: @param  string $bin
  
  @return $this