code: def message_as_clear(self, body_parts, attachments, parts, msg):
      m = self._str_msg(msg)
      m.clear()
      self.assertEqual(len(m), 0)
      self.assertEqual(list(m.items()), [])
      self.assertIsNone(m.get_payload())
      self.assertEqual(list(m.iter_parts()), [])
  
imports: import unittest
  import textwrap
  from email import policy, message_from_string
  from email.message import EmailMessage, MIMEPart
  from test.test_email import TestEmailBase, parameterize
label_desc: Use image node_id 16 for calling the TestEmailMessageBase obj's underlying member method code with example usage: obj.message_as_clear(body_parts, attachments, parts, msg) without return types