Problem using ctrlp_custom_ignore

[lsiden]

I need better documentation explaining _ctrlp_customignore. I put this in .vimrc but it had no effect:

"let g:ctrlp_custom_ignore = { 'dir': '(__pycache__|venv|build)$' }

It just takes a regular expression, right?

[tacahiroy]

With basic Vim's regexp the configuration would be like either of examples below:

let g:ctrlp_custom_ignore = { 'dir': '\v(__pycache__|venv|build)$' }

or

let g:ctrlp_custom_ignore = { 'dir': '\(__pycache__\|venv\|build\)$' }

If none of them works can you show me all ctrlp related configs in your vimrc please.