code: def test_multipart_invalid_cte(self):
      with self._raise_point(
          errors.InvalidMultipartContentTransferEncodingDefect
      ):
          msg = self._str_msg(
              self.multipart_msg.format(
                  "\nContent-Transfer-Encoding: base64"
              )
          )
      if self.raise_expected:
          return
      self.assertEqual(len(self.get_defects(msg)), 1)
      self.assertIsInstance(
          self.get_defects(msg)[0],
          errors.InvalidMultipartContentTransferEncodingDefect,
      )
  
imports: import textwrap
  import unittest
  import contextlib
  from email import policy
  from email import errors
  from test.test_email import TestEmailBase
label_desc: Use image node_id 4 for calling the TestDefectsBase obj's underlying member method code with example usage: obj.test_multipart_invalid_cte() without return types