from flask import Flask

app = Flask(__name__)


@app.route('/')
def index():
    """Create the home page of the web app.

    Link to the second page.
    """
    return """
    <html>
        <head>
            <title>Hello world</title>
        </head>
        <body>
            Hello world!
            <br>
            <a href='/second_page.html'>LINK</a> to second page.
        </body>
    </html>
    """


@app.route('/second_page.html')
def second_page():
    """Show the second page.

    Link to the third page.
    """
    return """
    <html>
        <head>
            <title>Hello world second page</title>
        </head>
        <body>
            Second page !!!
            <a href='/third_page.html'>LINK</a> to page 3.
        </body>
    </html>
    """


@app.route('/third_page.html')
def third_page():
    """Show the third page of the web app."""
    return """
    <html>
        <head>
            <title>Hello world third page</title>
        </head>
        <body>
            Page 3 !!!
        </body>
    </html>
    """

from flask import Flask

app = Flask(__name__)


@app.route('/')
def index():
    """Create the home page of the web app.

    Link to the second page.
    """
    return """
    <html>
        <head>
            <title>Hello world</title>
        </head>
        <body>
            Hello world!
            <br>
            <a href='/second_page.html'>LINK</a> to second page.
        </body>
    </html>
    """


@app.route('/second_page.html')
def second_page():
    """Show the second page.

    Link to the third page.
    """
    return """
    <html>
        <head>
            <title>Hello world second page</title>
        </head>
        <body>
            Second page !!!
            <a href='/third_page.html'>LINK</a> to page 3.
        </body>
    </html>
    """


@app.route('/third_page.html')
def third_page():
    """Show the third page of the web app."""
    return """
    <html>
        <head>
            <title>Hello world third page</title>
        </head>
        <body>
            Page 3 !!!
        </body>
    </html>
    """

Create the home page of the web app.      Link to the second page. <html>         <head>             <title>Hello world</title>         </head>         <body>             Hello world!             <br>             <a href='/second_page.html'>LINK</a> to second page.         </body>     </html> Show the second page.      Link to the third page. <html>         <head>             <title>Hello world second page</title>         </head>         <body>             Second page !!!             <a href='/third_page.html'>LINK</a> to page 3.         </body>     </html> Show the third page of the web app. <html>         <head>             <title>Hello world third page</title>         </head>         <body>             Page 3 !!!         </body>     </html>