code: function send_commands(cmds, cb) {
          function callback(value) {
              if (cb) cb(value)
              this.locked = false
          }
          function run() { 
              if (this.locked = cmds.length > 0) send_command(cmds.shift(), (success) => {
                  if (success) setTimeout(run, 200);
                  else callback(false);
              });
              else callback(true); 
          };
          if(!this.locked) run();
      }
docs: Send Multiple Commands