Need Support- flask gives me 404 not found

Hello there Hasan, how are you doing? Hope you are fine! I´m a student of Build and Sell APIs - Establish a New Income Stream. I´m facing an issue in lesson "Build Your First API", particularly in Build With AI ..the browser can not access the API. And the following message is shown to me "Not Found
The requested URL was not found on the server. If you entered the URL manually please check your spelling and try again." Then I get this return on VS Code "127.0.0.1 - - [16/Jul/2024 21:10:32] "GET / HTTP/1.1" 404 -"

I have no ideia how to figure out what is happening ..

This is the code I have saved in app.py

from flask import Flask, request, jsonify
import requests

app = Flask(__name__)

YOUTUBE_SUGGESTION_URL = "http://suggestqueries.google.com/complete/search"

@app.route('/youtube-suggestions', methods=['GET'])
def youtube_suggestions():
query = request.args.get('query')
if not query:
return jsonify({"error": "Query parameter is required"}), 400

params = {
'client': 'youtube',
'ds': 'yt',
'q': query,
}

try:
response = requests.get(YOUTUBE_SUGGESTION_URL, params=params)
response.raise_for_status()

# YouTube returns the suggestions in a JSONP format, we need to strip the padding
suggestions = response.text
suggestions = suggestions[suggestions.index('(') + 1:suggestions.rindex(')')]

suggestions_json = suggestions.strip()
suggestions_list = eval(suggestions_json)[1]

return jsonify({"suggestions": suggestions_list})

except requests.RequestException as e:
return jsonify({"error": str(e)}), 500

if __name__ == '__main__':
app.run(debug=True)