Function attention_fallback 

pub fn attention_fallback(
    query: Tensor<4>,
    key: Tensor<4>,
    value: Tensor<4>,
    mask: Option<Tensor<4, Bool>>,
    attn_bias: Option<Tensor<4>>,
    options: AttentionModuleOptions,
) -> Tensor<4>

Exports attention fallback to test backend’s attention against.