public function toXdr()
    {
        $bytes = '';

        // Source Account
        $bytes .= XdrEncoder::optional($this->sourceAccount);

        // Type
        $bytes .= XdrEncoder::unsignedInteger($this->type);

        return $bytes;
    }
public function toXdr()
    {
        $bytes = '';

        // Source Account
        $bytes .= XdrEncoder::optional($this->sourceAccount);

        // Type
        $bytes .= XdrEncoder::unsignedInteger($this->type);

        return $bytes;
    }
public function toXdr ( ) { $ bytes = '' ; // Source Account $ bytes .= XdrEncoder :: optional ( $ this -> sourceAccount ) ; // Type $ bytes .= XdrEncoder :: unsignedInteger ( $ this -> type ) ; return $ bytes ; }
Child classes MUST call this method to get the header for the operation
and then append their body

@return string
Child classes MUST call this method to get the header for the operation and then append their body