code: function formatType6(indexedPropPath) {
      return function(index_) {
        return function(f) {
          return function(t) {
            return function(propPath_) {
              var indexedPropPath_ = Z.concat ([index_], propPath_);
              var p = isPrefix (indexedPropPath_) (indexedPropPath);
              var q = isPrefix (indexedPropPath) (indexedPropPath_);
              return p && q ? f : p ? I : _;
            };
          };
        };
      };
    }
docs: formatType6 :: PropPath -> Integer -> (String -> String) -> Type -> PropPath -> String -> String