      interpolated2 = nlp.config.interpolate()
      assert interpolated2["corpora"]["train"]["path"] == ""
      assert interpolated2["components"]["tagger"]["model"]["tok2vec"]["width"] == 342
      nlp2 = English.from_config(interpolated)
      assert nlp2.config["corpora"]["train"]["path"] == ""
      assert nlp2.config["components"]["tagger"]["model"]["tok2vec"]["width"] == 342
  
  
  def test_config_optional_sections():
      config = Config().from_str(nlp_config_string)
 
</s> remove     assert interpolated2["corpora"]["train"]["path"] == ""
 </s> add     assert interpolated2["corpora"]["train"]["path"] is None </s> remove     assert interpolated["corpora"]["train"]["path"] == ""
 </s> add     assert interpolated["corpora"]["train"]["path"] is None </s> remove train = ""
dev = ""
 </s> add train = null
dev = null </s> remove train = ""
dev = ""
 </s> add train = null
dev = null </s> remove train = ""
dev = ""
 </s> add train = null
dev = null
    assert nlp2.config["corpora"]["train"]["path"] is None
      interpolated2 = nlp.config.interpolate()
      assert interpolated2["corpora"]["train"]["path"] == ""
      assert interpolated2["components"]["tagger"]["model"]["tok2vec"]["width"] == 342
      nlp2 = English.from_config(interpolated)
    assert nlp2.config["corpora"]["train"]["path"] is None
      assert nlp2.config["components"]["tagger"]["model"]["tok2vec"]["width"] == 342
  
  
  def test_config_optional_sections():
      config = Config().from_str(nlp_config_string)
keep keep keep keep replace keep keep keep keep keep
 Make corpus paths default to None and improve errors 
spacy/tests/serialize/test_serialize_config.py