class_docstr: Mixin to test a bunch of common functionality in models
  deriving from RecommenderBase
code: def test_dtype(self):
      # models should be able to accept input of either float32 or float64
      item_users = get_checker_board(50)
      model = self._get_model()
      model.fit(item_users.astype(np.float64), show_progress=False)
  
      model = self._get_model()
      model.fit(item_users.astype(np.float32), show_progress=False)
  
imports: import os
  import pickle
  import random
  import tempfile
  import numpy
  import pytest
  from numpy.testing import assert_array_equal
  from scipy.sparse import coo_matrix, csr_matrix
  from implicit.evaluation import precision_at_k
  from implicit.nearest_neighbours import ItemItemRecommender
  from implicit.utils import ParameterWarning
label_desc: Use image node_id 15 for calling the RecommenderBaseTestMixin obj's underlying member method code with example usage: obj.test_dtype() without return types