Function radius_search_spatial_tensor_parallel_into 

pub fn radius_search_spatial_tensor_parallel_into<I: ChunkedRadiusSearchIndex + Sync>(
    index: &I,
    x: &[f32],
    y: &[f32],
    z: &[f32],
    tensor: &SpatialTensor<'_>,
    radius: f32,
    out: &mut Vec<(usize, Neighbor)>,
)

Parallel radius search, appending (query_index, neighbor) pairs to out.