Write a new completer Docs

[amadeus]

I am interested in potentially writing a new completor for JS using Flow. However as it stands the current docs are empty for Write a new completer. Is there at least a gist or a recommended place to start looking into this?

[maralla]

Here is an example of how to write a new completer: https://github.com/maralla/completor-swift.

If the completer is the default of completor.vim, you should import the new completer eagerly in a ftplugin to override the default one.