docs: def get_accessibles(request, roles=None):
          """
          Returns the list of *dictionnaries* for which the accounts are
          accessibles by ``request.user`` filtered by ``roles`` if present.
          """
          results = []
          for role_name, organizations in six.iteritems(request.session.get(
                  'roles', {})):
              if roles is None or role_name in roles:
                  results += organizations
          return results