input: Write a python function to create a simple echo server using sockets.
  assert isinstance(create_echo_server(), socket.socket)
output: import socket
  
  def create_echo_server():
      server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
      server_socket.bind(('localhost', 0))  # Bind to an available port
      server_socket.listen(1)
      
      def echo_client_handler(client_socket):
          while True:
              data = client_socket.recv(1024)
              if not data:
                  break
              client_socket.sendall(data)
          client_socket.close()
  
      while True:
          client_socket, _ = server_socket.accept()
          echo_client_handler(client_socket)
  
      return server_socket