I thought you were crazy so I looked it up on TCM. You are sane.
It took no less than six writers to transform Murray Burnett and Joan Alison's un-produced play 'Everybody Comes to Rick' into Casablanca, taking a conventional exotic romance (patterned after Algiers (1938) and Only Angels Have Wings, 1939) and investing it with a subtle, richly-textured brand of drama all its own.
Don't be too quick on the trigger regarding that last part there.
 <}B^)