Function einsum_into_with_pool 

pub fn einsum_into_with_pool<T: EinsumScalar>(
    notation: &str,
    operands: Vec<EinsumOperand<'_>>,
    output: StridedViewMut<'_, T>,
    alpha: T,
    beta: T,
    size_dict: Option<&HashMap<char, usize>>,
    pool: Option<&mut BufferPool>,
) -> Result<()>

Parse and evaluate an einsum expression into an output buffer with optional buffer pool reuse.

output = alpha * einsum(operands) + beta * output

Pass Some(&mut pool) to reuse intermediate buffers across calls. Pass None for independent allocation (equivalent to einsum_into).