'Index over trimmed volume types.'

def index(self, request, volume_types):

    volume_types_list = [self.show(request, volume_type, True) for volume_type in volume_types]
    volume_type_links = self._get_collection_links(request, volume_types, 'types')
    volume_types_dict = dict(volume_types=volume_types_list)
    if volume_type_links:
        volume_types_dict['volume_type_links'] = volume_type_links
    return volume_types_dict
