code: def msg_as_input(self, msg):
      m = message_from_bytes(msg, policy=policy.SMTP)
      b = io.BytesIO()
      g = BytesGenerator(b)
      g.flatten(m)
      self.assertEqual(b.getvalue(), msg)
  
file_path: cpython/Lib/test/test_email/test_inversion.py
imports: import io
  import unittest
  from email import policy, message_from_bytes
  from email.message import EmailMessage
  from email.generator import BytesGenerator
  from test.test_email import TestEmailBase, parameterize
label_desc: Use image node_id 1 for calling the TestInversion obj's underlying member method code with example usage: obj.msg_as_input(msg) without return types