input: Write a python function to create a simple HTTP server that listens on a specified port and serves files from the current directory.
  assert create_http_server(8000) == "Server started at port 8000"
  assert create_http_server(8080) == "Server started at port 8080"
output: def create_http_server(port):
      from http.server import SimpleHTTPRequestHandler, HTTPServer
      import threading
  
      def start_server():
          server = HTTPServer(('localhost', port), SimpleHTTPRequestHandler)
          server.serve_forever()
  
      threading.Thread(target=start_server, daemon=True).start()
      return f"Server started at port {port}"