code: def find_workflow_path(self):
          
          for pth in settings.WORKFLOW_PACKAGES_PATHS:
              path = "%s/%s.bpmn" % (pth, self.current.workflow_name)
              if os.path.exists(path):
                  return path
          err_msg = "BPMN file cannot found: %s" % self.current.workflow_name
          log.error(err_msg)
          raise RuntimeError(err_msg)
docs: Tries to find the path of the workflow diagram file
          in `WORKFLOW_PACKAGES_PATHS`.
  
          Returns:
              Path of the workflow spec file (BPMN diagram)