De0 Nano ADC demo coding explanations

Hello everyone, there's a code line (below) I don't understand from the De0-Nano ADC demo. I tried to find out about the (?) but as far as I can get, there is only (?: conditional) in verilog syntax. Is it mean when go_en is high, the oSCLK is equal to iCLK?
Can somebody explain?

assign oSCLK = (go_en)? iCLK:1;