Function streaming_verilog_folding 

pub fn streaming_verilog_folding(
    sets: &[ColumnSet],
    layout: &ImageLayout,
    folds: usize,
) -> String

streaming_verilog with each unit folding a job’s sums into its output slot over folds fold lanes, 1, 2, 4, 8 or 16 (fold_unit); 0 a unit that writes each sum as it is, streaming_verilog’s.