class_docstr: PosTag (Part of Speech Tagging Visualizer) Tests
docstr: Assert no errors occur during PosTagVisualizer integration
  with raw corpus to be parsed using nltk
docstr_tok: ["Assert","no","errors","occur","during","PosTagVisualizer","integration","with","raw","corpus","to","be","parsed","using","nltk"]
code: def test_nltk_wordpunct_raw(self):
      """
      Assert no errors occur during PosTagVisualizer integration
      with raw corpus to be parsed using nltk
      """
      visualizer = PosTagVisualizer(
          parser="nltk_wordpunct", tagset="penn_treebank"
      )
      visualizer.fit(sonnets)
      visualizer.ax.grid(False)
  
      self.assert_images_similar(visualizer)
  
imports: import pytest
  import matplotlib.pyplot
  from tests.base import VisualTestCase
  from tests.base import IS_WINDOWS_OR_CONDA
  from yellowbrick.text.postag import *
  from yellowbrick.exceptions import YellowbrickValueError
label_desc: Use image node_id 9 for calling the TestPosTag obj's underlying member method code with example usage: obj.test_nltk_wordpunct_raw() without return types