shorten FastAPI app.py with APIRouter

FastAPI app.py files can get long. Use APIRouter to structure the application into different files. In api/elsewhere.py,

router = APIRouter(prefix="/elsewhere")
 
@router.get("/somewhere/")
def func():
	pass

and then in app.py

from .api import elsewhere
 
app = FastAPI()
app.include_router(elsewhere.router)