Assign 3 variables to 2 values

[ruicao-github]

Dear David,
thank you for the excellent book, as a beginner, I learned a lot.

In the dart code from chapter 8 flying pigs (Chapter_08/FlyingPigs/web/flyingpigs.dart), on line 15, int pigX, pigY, score = 0, speed;, how is it possible to assign 3 variables to 2 values? Is speed a tuple? I have not found the variable speed being initialized anywhere in the code. I am confused.
I attach the original code below for your reference.
Best,
Rui