12.3 Building the App:

Now we have to “build” the app, which packages up the app and uploads it to your current project

cd ./ex/
dx build -f findNi

## WARNING:dxpy:name "findNi" should be all lowercase
## INFO:dxpy:Deleting applet(s) applet-Fggq7Jj0pgP0bYy934Kj7Z06
## {"id": "applet-Fggv7Xj0pgPBQP1P5PfPjzZ0"}