class_docstr: Test PFMFeaturizer.
docstr: Set up test.
docstr_tok: ["Set","up","test","."]
code: def setUp(self):
      """
      Set up test.
      """
      self.msa = np.array([["ABC", "BCD"], ["AAA", "AAB"]])
      self.featurizer = PFMFeaturizer()
      self.max_length = 100
  
file_path: deepchem/deepchem/feat/tests/test_position_frequency_matrix_featurizer.py
imports: import unittest
  import numpy
  from deepchem.feat.sequence_featurizers.position_frequency_matrix_featurizer import PFMFeaturizer, CHARSET, PFM_to_PPM
label_desc: Use image node_id 1 for calling the TestPFMFeaturizer obj's underlying member method code with example usage: obj.setUp() without return types