Function einsum2_with_backend_into 

pub fn einsum2_with_backend_into<T, B, ID>(
    c: StridedViewMut<'_, T>,
    a: &StridedView<'_, T>,
    b: &StridedView<'_, T>,
    ic: &[ID],
    ia: &[ID],
    ib: &[ID],
    alpha: T,
    beta: T,
) -> Result<()>
where
    T: ScalarBase,
    B: BgemmBackend<T> + BackendConfig,
    ID: AxisId,

Binary einsum with a pluggable GEMM backend.

Like einsum2_into but works with any ScalarBase type and dispatches to the caller-provided GEMM backend B. Views must use Identity element operations (the default).

External crates can implement BgemmBackend for custom scalar types (e.g., tropical semiring) and pass the backend here.