docs: function execSeries(cmds, done) {
    var out = [];
    async.forEachSeries(cmds, function(cmd, next) {
      exec(cmd, function(err, stdout, stderr) {
        out.push({
          stdout: stdout,
          stderr: stderr,
          err: err
        });
        next();
      });
    }, function() {
      done(null, out);
    });
  }