'Retrieves and formats a single element of the requested entity.'

def _item(self, request, id, do_authz=False, field_list=None, parent_id=None):

    kwargs = {'fields': field_list}
    action = self._plugin_handlers[self.SHOW]
    if parent_id:
        kwargs[self._parent_id_name] = parent_id
    obj_getter = getattr(self._plugin, action)
    obj = obj_getter(request.context, id, **kwargs)
    if do_authz:
        policy.enforce(request.context, action, obj, pluralized=self._collection)
    return obj
