endpoint_out.bEndpointAddress return None in escpos-python

Question

when i run my code the printer.py returns the below error

Error: printer.py

Traceback (most recent call last):
  File "/usr/lib/python2.7/SocketServer.py", line 596, in process_request_thread
    self.finish_request(request, client_address)
  File "/usr/lib/python2.7/SocketServer.py", line 331, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "/usr/lib/python2.7/SocketServer.py", line 652, in __init__
    self.handle()
  File "/usr/lib/python2.7/BaseHTTPServer.py", line 340, in handle
    self.handle_one_request()
  File "/usr/lib/python2.7/BaseHTTPServer.py", line 328, in handle_one_request
    method()
  File "server.py", line 67, in do_GET
    print_dev = Usb(connected[0]['vendor'], connected[0]['product'])
  File "/home/acespritech/projects/Printing Code/escpos/printer.py", line 32, in __init__
    self.open()
  File "/home/acespritech/projects/Printing Code/escpos/printer.py", line 60, in open
    self.out_ep = endpoint_out.bEndpointAddress
AttributeError: 'NoneType' object has no attribute 'bEndpointAddress'