new_contents: from .middleware import CORSMiddleware
  
  
  class AsyncCORSMiddleware(CORSMiddleware):
      async def process_resource_async(self, req, resp, resource, *args):
          if not getattr(resource, 'cors_enabled', self.default_enabled):
              return
          cors = getattr(resource, 'cors', self.cors)
          cors.process(req, resp, resource)
  
subject: Create async_middleware.py