yourapp/
    __init__.py
    static/
    templates/
        home/
        blog/
    views/
        __init__.py
        home.py
        blog.py
    models.py

# home.py

home = Blueprint('home', __name__)

@home.route('/')
def index():
    ...
    return render_template('index.html',
                           url=call_some_shared_code)

# blog.py

blog = Blueprint('blog', __name__)

@blog.route('/')
def index():
    ...
    return render_template('blog.html',
                           url=call_some_shared_code)

yourapp/
    __init__.py
    static/
    templates/
        home/
        blog/
    views/
        __init__.py
        home.py
        blog.py
    models.py
    common.py  # <-- shared code

#common.py

def get_url():
    return session.get('url') or current_app.config.get('URL')

def get_connection():
    return client.connect(get_url(),
                          auth_type=session.get('auth_type'),
                          username=session.get('username'),
                          password=session.get('password'))

# blog.py
from yourapp import common

blog = Blueprint('blog', __name__)

@blog.route('/')
def index():
    ...
    client = client.get_client('group',
                               connection=common.get_connection())
    ...
    return render_template('blog.html',
                           url=common.get_url())