change port flask runs on code example

Example 1: flask give port number

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=80)

Example 2: how to change port in flask app

if __name__ == "__main__":
    app.run(host='127.0.0.1', port=5002)

Example 3: flask port

from flask import Flask

app = Flask(__name__)

if __name__ == '__main__':
      app.run(port=80)

# Also make sure that nothing else is running on port 80