[rules-users] Retrieve values from a Map

I am new to drools and currently using version 5.1 for my testing. I am facing an issue with retrieving a value from Map if a key is present In my drl if i do this $c : Client (language contains "Japanese" , lang : language -> (language.get("Japanese").equals("Expert"))) it works ...but if i want to retrieve the value of the key i am not sure how to go about it . I tried various approaches but none of them worked i would like to do something like $c : Client (language contains "Japanese", $langValue : language.get("Japanese")) Can some one please guide me how to go about it . Regards, Manav