sbop does not output valid mcfunction

[supercam19]

Using sbop will not output valid mcfunction code:

main.databind:

func main
   var variable1 := 5
   var variable2 := 2
   sbop gvar variable1 *= gvar variable2
end

main.mcfunction

scoreboard objectives add variable1 dummy
scoreboard players set --databind variable1 5
scoreboard objectives add variable2 dummy
scoreboard players set --databind variable2 2
--databind variable1 *= --databind variable2

The error here is on line 5 - the expected result is: scoreboard players operation --databind variable1 *= --databind variable2