class_docstr: Generates output from a Message object tree.
  
  This basic generator writes the message to the given file object as plain
  text.
code: def _handle_multipart_signed(self, msg):
      # The contents of signed parts has to stay unmodified in order to keep
      # the signature intact per RFC1847 2.1, so we disable header wrapping.
      # RDM: This isn't enough to completely preserve the part, but it helps.
      p = self.policy
      self.policy = p.clone(max_line_length=0)
      try:
          self._handle_multipart(msg)
      finally:
          self.policy = p
  
imports: import re
  import sys
  import time
  import random
  from copy import deepcopy
  from io import StringIO, BytesIO
  from email.utils import _has_surrogates
label_desc: Use image node_id 13 for calling the Generator obj's underlying member method code with example usage: obj._handle_multipart_signed(msg) without return types