code: def test_knows_x(self):
      mf = MF(1, 1, seed=123)
      dataset = Dataset.from_uir(self.data)
      mf.fit(dataset)
  
      self.assertTrue(mf.knows_user(7))
      self.assertFalse(mf.knows_item(13))
  
      self.assertTrue(mf.knows_item(3))
      self.assertFalse(mf.knows_item(16))
  
file_path: cornac/tests/cornac/models/test_recommender.py
imports: import unittest
  from cornac.data import BasketDataset, Dataset, SequentialDataset, Reader
  from cornac.models import MF, GPTop, SPop, NextBasketRecommender, NextItemRecommender
label_desc: Use image node_id 2 for calling the TestRecommender obj's underlying member method code with example usage: obj.test_knows_x() without return types