code: def test_flushes_stream_after_prompt(self):
      # see issue 1703
      stream = mock.Mock(spec=StringIO)
      input = StringIO("input_string")
      getpass._raw_input("some_prompt", stream, input=input)
      stream.flush.assert_called_once_with()
  
imports: import getpass
  import os
  import unittest
  from io import BytesIO, StringIO, TextIOWrapper
  from unittest import mock
  from test import support
label_desc: Use image node_id 1 for calling the GetpassRawinputTest obj's underlying member method code with example usage: obj.test_flushes_stream_after_prompt() without return types