* Send the invoice to the client.
    * Collect the money from the client.
    * Send a notification back to the API user (the external developer), as a callback.
        * At this point is that the API will somehow send a POST request to the
            external API with the notification of the invoice event
            (e.g. "payment successful").
    """
    # Send the invoice, collect the money, send the notification (the callback)

engine = sqlalchemy.create_engine(
    DATABASE_URL, connect_args={"check_same_thread": False}
)
metadata.create_all(engine)


class NoteIn(BaseModel):
    text: str
    completed: bool


class Note(BaseModel):
    id: int
    text: str
    completed: bool


app = FastAPI()


@app.on_event("startup")
async def startup():
    await database.connect()


@app.on_event("shutdown")