insure export is capital

lib/bus.js

@@ -19,4 +19,6 @@ class Bus {
 
 } // end of Bus Class
 
-module.exports = Bus;
+module.exports = {
+  Bus
+};

lib/device.js

@@ -30,7 +30,6 @@ class Device {
     return this.bus.writeByte_p(this.address, cmd, byte)
   }
 
-
   read2(cmd) {
     return this.bus.readWord_p(this.address, cmd)
   }
@@ -43,8 +42,8 @@ class Device {
   readBytes() {}
   writeBytes() {}
 
-
-
 }
 
-    module.exports = Device;
+module.exports = {
+  Device
+}