code: @Override
      public void include(InputStream is, Charset cs, String source) throws IOException
      {
          if (cursor != end)
          {
              release();
          }
          if (includeStack == null)
          {
              includeStack = new ArrayDeque<>();
          }
          includeStack.push(includeLevel);
          includeLevel = new IncludeLevel(getFeaturedReadable(Channels.newChannel(is), cs, features), source);
      }
docs: Include InputStream at current input. InputStream is read as part of
  input. When InputStream ends, input continues using current input.
  
  <p>Included stream is closed at eof
  
  @param is Incuded input
  @param cs Character set
  @param source Description of the source
  @throws IOException