what port to use flask code example

Example 1: how to change port in flask app

from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello World!"

if __name__ == '__main__':
    app.run(host="localhost", port=8000, debug=True)

Example 2: 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