val slop : ?strand:bool ‑> ?header:bool ‑> mode:[ `both of int | `left of int | `right of int | `both_pct of float | `left_pct of float | `right_pct of float ] ‑> 'a Bistro.Std.workflow ‑> Ucsc_gb.chrom_sizes Bistro.Std.workflow ‑> Bistro.EDSL.command