DT support for 33 DK

[Manas_punjabi]

#define GPIO_SPEC_AND_COMMA(button_or_led) GPIO_DT_SPEC_GET(button_or_led, gpios),

I find this code in the buttons and led .c file 

I tried finding what is does , but I couldn't .

I just need help to understand what id does and how to use it!

[Manas_punjabi]

I was referring the peripheral UART sample