code: def find(serial_number=None):
          
          try:
              hidraw = hid.device(VENDOR_ID,PRODUCT_ID,serial_number)
              hidraw.open(VENDOR_ID,PRODUCT_ID,serial_number)
              # hidraw = hid.device(VENDOR_ID,PRODUCT_ID,unicode(serial_number))
              # hidraw.open(VENDOR_ID,PRODUCT_ID,unicode(serial_number))
          except IOError as e:  # python2
              raise Blink1ConnectionFailed(e)
              hidraw = None
          except OSError as e:  # python3
              raise Blink1ConnectionFailed(e)
              hidraw = None
  
          return hidraw
docs: Find a praticular blink(1) device, or the first one
          :param serial_number: serial number of blink(1) device (from Blink1.list())