Function set0_gadget 

pub fn set0_gadget<W>() -> LogicGadget<W>
where
    W: Clone + Default + From<i32>,

Create a SET0 gadget (constant false).

1-variable SpinGlass that prefers config 0 (spin -1 in Rust convention). h = [1] (negated from Julia’s [-1] to account for different spin convention)