code: public static Func1<Iterable<String>, String> toJoinedString(final String delimiter) {
          return new Func1<Iterable<String>, String>() {
              @Override
              public String call(Iterable<String> iterable) {
                  StringBuilder builder = new StringBuilder();
                  boolean first = true;
                  for (String string : iterable) {
                      if (first)
                          first = false;
                      else
                          builder.append(delimiter);
                      builder.append(string);
                  }
                  return builder.toString();
              }
          };
      }
docs: Returns a method that can be used with {@link solid.stream.Stream#collect(Func1)}
  to convert an iterable stream of {@link String} type into a joined string.
  
  @param delimiter a delimiter
  @return a method that converts an iterable stream of {@link String} type into a joined string.