def gen_random_usernames():
 while 1:
  (yield hex(int((random.random() * (16 ** 12))))[2:].zfill(12).decode('ASCII'))

def gen_random_usernames ( ) : while 1 : ( yield hex ( int ( ( random . random ( ) * ( 16 ** 12 ) ) ) ) [ 2 : ] . zfill ( 12 ) . decode ( 'ASCII' ) )
yield random 12-hex-digit unicodes .