code: function preproc(inst, prog, argv, event, fin) {
      var info = findPreprocs(inst, prog, [], []);
      function step(procs, parts, list) {
          if (!procs || procs.length < 1) {
              return fin(null, list);
          }
          var part = parts.shift();
          var proc = procs.shift();
          var ctx = {
              id: inst.counter,
              seed: inst.seednum,
              store: inst.storage,
              argv: argv,
              event: event
          };
          return proc.call(ctx, part, list, function(err, _list) {
              if (err) return fin(err);
              return step(procs, parts, _list);
          });
      }
      return step(info.procs, info.parts, info.list);
  }
docs: Run any preprocessors that are present in the program, please