Function try_backward 

pub fn try_backward<Op: Primitive>(
    output_key: &ValueKey<Op>,
    output_trace: Option<&Trace<Op>>,
    seed: Arc<Op::Operand>,
    executor: &mut impl BackwardExecutor<Op>,
    ctx: &mut Op::ADContext,
) -> ADRuleResult<HashMap<ValueKey<Op>, Arc<Op::Operand>>>
where
    Op::InputKey: ADKey,

Execute reverse-mode AD over an eager trace.