Function zkevm_circuits::copy_circuit::constrain_must_terminate

pub fn constrain_must_terminate<F: Field>(
    cb: &mut BaseConstraintBuilder<F>,
    meta: &mut VirtualCells<'_, F>,
    q_enable: Column<Fixed>,
    tag: &BinaryNumberConfig<CopyDataType, 3>
)

Verify that is_last goes to 1 at some point.