Function iter_blas 

fn iter_blas<'snatch_guard: 'buffers, 'buffers>(
    blas_iter: impl Iterator<Item = &'buffers OwnedBlasBuildEntry<ArcReferences>>,
    build_command: &mut AsBuild,
    input_barriers: &mut Vec<BufferBarrier<'buffers, dyn DynBuffer>>,
    scratch_buffer_blas_size: &mut u64,
    blas_storage: &mut Vec<BlasStore<'buffers>>,
    state: &mut EncodingState<'snatch_guard, '_>,
) -> Result<(), BuildAccelerationStructureError>

iterates over the blas iterator, and it’s geometry, pushing the buffers into a storage vector (and also some validation).