When GPIO is () is ()
when gpio (0 v) is [high v] :: extension hat
Category Raspberry Pi GPIO
Type Hat
Introduced in 3.0

The when gpio () is () block is a Raspberry Pi GPIO block and a hat block. Its options for the first input are the numbers 0 thru 27, with each number representing a GPIO pin. The second options are "high" and "low", representing a state that the pin can be set to. The hat block activates when the state has been set for that pin.