[NTG-context] python parse/formatter example on the wiki

I was trying the example of "writing a parse/formatter" under "Verbatim text". The python formatter runs successfully. But when I compile the text file with all the definitions included, an error occurs. <inserted text> } <to be read again> \endgroup \buff_verbatim_type_block_verbatim_indeed ...ines \dostoptagged \csname #2\e... It could be implemented forcefully, but definitely not an excuse to ignore this error. Any solutions?