docs: function(filter,cb) {
        if (!filter) {
          filter = {};
        } else if (typeof filter == "function") {
          cb = filter;
          filter = {};
        } else if (typeof filter == "string") {
          filter = {device_type:filter}; // Backwards compatibility
        }
        var opts = {
          url: uri + 'devices',
          method: 'GET',
          qs: qs,
          json: true
        };
        request(opts,function(e,r,b) {
          if (e) cb(e)
          else if (b.result===1) cb(null, utils.filter(filter,b.data))
          else cb({statusCode:b.id||200,error:b.error})
        });
      }