OSError: [Errno 98] Address already in use with Gunicorn (Dash app deployment)

Solution
def register_dash_app(flask_app):

    dash_app = dash.Dash(external_stylesheets=[dbc.themes.BOOTSTRAP],
                    server=flask_app,
                    name='Example',
                    url_base_pathname="/example/")

    dash_app.layout = html.Div([
        html.H1('Hi there!'),
        html.H4(hello_world())
        ]
    )

    return dash_app
import flask

from rwg_app.dash_app import register_dash_app
from flask import Flask

app = Flask(__name__)

register_dash_app(app)

@app.route("/dashboard")
def render_dashboard():
    return flask.redirect('/rwg/')