let create
?(wrap_bam_node = fun _ x -> x)
?(wrap_vcf_node = fun _ x -> x)
?(wrap_gtf_node = fun _ x -> x)
?(options=[])
~reference_build ~work_dir ~machine () =
{reference_build; work_dir; machine; options;
wrap_bam_node; wrap_vcf_node; wrap_gtf_node}