src/Refinery.php
protected function attachItem($attachment)
    {
        if ( ! method_exists($this, $attachment)) {
            throw new RefineryMethodNotFound(
                "No attachment set with the name '{$attachment}' on '" . get_class($this) . "'."
            );
        }

        return $this->$attachment();
    }
protected function attachItem($attachment)
    {
        if ( ! method_exists($this, $attachment)) {
            throw new RefineryMethodNotFound(
                "No attachment set with the name '{$attachment}' on '" . get_class($this) . "'."
            );
        }

        return $this->$attachment();
    }
Check the attachment method exists on the class being attached, if it
does then run the method.

@param  string $attachment
@return mixed
@throws RefineryMethodNotFound