Where is the GPIO interrupt function for GPIO_toggle()?

Hi,

When I run project gpiointerrupt_EK_TM4C1294XL_TI_TivaTM4C1294NCPDT for 1294 LaunchPad, I don't see where GPIO interrupt is cleared for the following task:

void gpioButtonFxn1(void)
{
    /* Clear the GPIO interrupt and toggle an LED */
    GPIO_toggle(Board_LED1);

    if (count++ == 100) {
        count = 0;
    }
}

I don't see the declaration of 

GPIO_toggle()


How is the interrupt cleared?
Thanks,