code: def test_no_sign_request(monkeypatch):
      """If AWS_NO_SIGN_REQUEST is set do not default to aws_unsigned=False"""
      monkeypatch.setenv("AWS_NO_SIGN_REQUEST", "YES")
      assert AWSSession().unsigned
  
imports: from unittest import mock
  import pytest
  from fiona.session import DummySession, AWSSession, Session, OSSSession, GSSession, SwiftSession, AzureSession
label_desc: Use image node_id 29 for calling a global function with example usage: test_no_sign_request(monkeypatch) without return types