code: private static int quote(final StringBuilder target, final String string, final int start) {
          int i = quoteSingle(target, string, start);
          if (i < 0) i = quoteBlock(target, string, start, -i);
          return i;
      }
docs: Appends following part of string quoted to {@code target}.
  @param target
  @param string
  @param start
  @return index of first character that was not appended