def set_gpio_interrupt_edge(edge='<STR_LIT>'):
<EOL>start_time = time.time()<EOL>time_limit = start_time + FILE_IO_TIMEOUT<EOL>while time.time() < time_limit:<EOL><INDENT>try:<EOL><INDENT>with open(GPIO_INTERRUPT_DEVICE_EDGE, '<STR_LIT:w>') as gpio_edge:<EOL><INDENT>gpio_edge.write(edge)<EOL>return<EOL><DEDENT><DEDENT>except IOError:<EOL><INDENT>pass<EOL><DEDENT><DEDENT>
Set the interrupt edge on the userspace GPIO pin.

    :param edge: The interrupt edge ('none', 'falling', 'rising').
    :type edge: string