Hello World

from flask import Flask
app = Flask(__name__)


@app.route('/')
def hello_world():
    return 'Hello World'


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

Nome com hello

from flask import Flask
app = Flask(__name__)


@app.route('/hello/<name>')
def hello_name(name):
    return 'Hello {}!'.format(name)


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