Function parallel_step_array1 

pub fn parallel_step_array1<O, A>(
    optimizer: &mut O,
    params_list: &[Array1<A>],
    grads_list: &[Array1<A>],
) -> Result<Vec<Array1<A>>>
where
    O: Optimizer<A, Ix1> + Clone + Send + Sync,
    A: Float + ScalarOperand + Debug + Send + Sync,

Parallel processing for Array1 specifically (optimized path)