public function setCommand($command)
    {
        if (! in_array($command, self::VALID_COMMANDS)) {
            throw new InvalidArgumentException('Invalid command sent');
        }

        $this->command = $command;

        return $this;
    }
public function setCommand($command)
    {
        if (! in_array($command, self::VALID_COMMANDS)) {
            throw new InvalidArgumentException('Invalid command sent');
        }

        $this->command = $command;

        return $this;
    }
public function setCommand ( $ command ) { if ( ! in_array ( $ command , self :: VALID_COMMANDS ) ) { throw new InvalidArgumentException ( 'Invalid command sent' ) ; } $ this -> command = $ command ; return $ this ; }
Set the unique command for this transaction type.

@param string $command

@return self
Set the unique command for this transaction type .