code: def supports_merge(data):
      
      gffcompare_installed = config_utils.program_installed("gffcompare", data)
      return version(data) >= LooseVersion("1.2.0") and gffcompare_installed
docs: 1.2.0 and up supports the --merge option and a planned utility gffcompare
      (https://github.com/gpertea/stringtie/issues/29) will add the class codes
      which will remove the need for cufflinks merge