Run a storm query and yield Node() objects.

async def eval(self, text, opts=None, user=None):
        '''
        Run a storm query and yield Node() objects.
        '''
        if user is None:
            user = self.user

        # maintained for backward compatibility
        query = self.core.getStormQuery(text)
        with self.getStormRuntime(opts=opts, user=user) as runt:
            async for node, path in runt.iterStormQuery(query):
                yield node