code: def message_as_iter_parts(self, body_parts, attachments, parts, msg):
      def _is_multipart_msg(msg):
          return "Content-Type: multipart" in msg
  
      m = self._str_msg(msg)
      allparts = list(m.walk())
      parts = [allparts[n] for n in parts]
      iter_parts = (
          list(m.iter_parts()) if _is_multipart_msg(msg) else []
      )
      self.assertEqual(iter_parts, 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 3 for calling the TestEmailMessageBase obj's underlying member method code with example usage: obj.message_as_iter_parts(body_parts, attachments, parts, msg) and returns: unknown