fuel/fuel/packages/email/classes/email/driver/mandrill.php
public function add_merge_vars(array $merge_vars, $rcpt = null)
	{
		if (is_null($rcpt))
		{
			$this->merge_vars = $merge_vars;
		}
		else
		{
			$this->rcpt_merge_vars[$rcpt] = $merge_vars;
		}

		return $this;
	}
public function add_merge_vars(array $merge_vars, $rcpt = null)
	{
		if (is_null($rcpt))
		{
			$this->merge_vars = $merge_vars;
		}
		else
		{
			$this->rcpt_merge_vars[$rcpt] = $merge_vars;
		}

		return $this;
	}
public function add_merge_vars ( array $ merge_vars , $ rcpt = null ) { if ( is_null ( $ rcpt ) ) { $ this -> merge_vars = $ merge_vars ; } else { $ this -> rcpt_merge_vars [ $ rcpt ] = $ merge_vars ; } return $ this ; }
Add merge vars

@param  array $merge_vars  Key-value pairs
@param  mixed $rcpt        Null for global, string for recipient
@return array
Add merge vars