code: function expandUnknown(env) {
      return function(seen) {
        return function(value) {
          return function(extractor) {
            return function(type) {
              return type.type === UNKNOWN ?
                     _determineActualTypes (env, seen, extractor (value)) :
                     [type];
            };
          };
        };
      };
    }
docs: expandUnknown :: Array Type -> Array Object -> Any -> (a -> Array b) -> Type -> Array Type