content: from websockets.datastructures import Headers
  
  from .utils import DeprecationTestCase
  
  
  class BackwardsCompatibilityTests(DeprecationTestCase):
      def test_headers_class(self):
          with self.assertDeprecationWarning(
              "Headers and MultipleValuesError were moved "
              "from websockets.http to websockets.datastructures"
              "and read_request and read_response were moved "
              "from websockets.http to websockets.legacy.http",
          ):
              from websockets.http import Headers as OldHeaders
  
          self.assertIs(OldHeaders, Headers)
  