Autocomplete

Hi,
I am having difficulties getting auto-complete work in ob-ipython the same way it works in ipython shell

- autocompletion works in REPL, using the 'tab' or 'Esc-tab' keys.
- In the source block it does not work unless I open the editor `C-c C-v z'
- In any case I would like propositions of packages after `import` like in ipython shell but neither in REPL nor source block this works.

Also I looked for the `ob-ipython-completions` function but could not find it in my installation.

What could have gone wrong ?
Thank you