code: public static <T, K> Func1<Iterable<T>, SolidMap<K, T>> toSolidMap(final Func1<T, K> keyExtractor) {
          return toSolidMap(keyExtractor, new Func1<T, T>() {
              @Override
              public T call(T value) {
                  return value;
              }
          });
      }
docs: Returns a function that converts a stream into {@link SolidMap} using a given key extractor method.