code: private void recurse(Stream bounds, String arg) {
      // Refuse if we've reached our recursion limit.
      streamIndex++;
      if (streamIndex == streams.length) {
        return;
      }
  
      // Trim the '{' and '}' bounding characters.
      bounds.pos++;
      bounds.end--;
  
      // Set the bounds of the tag, allocating a new stream on the stack if necessary.
      if (streams[streamIndex] == null) {
        streams[streamIndex] = bounds.copy();
      } else {
        streams[streamIndex].setFrom(bounds);
      }
  
      // Execute the formatter recursively on the current bounds, then
      // pop the stack.
      format(streams[streamIndex], arg);
      streamIndex--;
    }
docs: Push a stream onto the stack and format it.