What does the following Python code do:
app = Flask(__name__)
FlaskInstrumentor().instrument_app(app)

# @instrument(span_name="do_work_function",existing_tracer=tracer)
@instrument
def do_work_function():
    time.sleep(0.1)


@app.route("/")
def hello_world():
    # You can still use the OpenTelemetry API as usual to create custom spans
    # within your trace

    with tracer.start_as_current_span("do_work"):
        for i in range(2):
            do_work_function()

    return "Hello, World!"

