elpy-occur-definitions integrated with helm

[humitos]

occur searches for occurrences in the current buffer, and elpy- uses a regex to search only for classes and functions. So, I want to integrate them with helm.

The problem is that elpy- and occur open a new buffer instead of returning a list of candidates (which is needed by helm as input).

(defun helm-elpy-occur-definitions ()
  (interactive)
  (helm :sources (occur "^ *\\(def\\|class\\) ")
        :buffer "*helm elpy occur definition*"))

[humitos]

(helm-occur)

does exactly what I want, but I didn't find a way yo call it with a pre-defined regex

[humitos]

Regex passed to helm-occur to get the same result ^ *\(def\|class\)