Undefined name 'Blog' in type hint

[cclauss]

$ flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics

./betterpython/7 - dealing with errors/monadic-error-handling/example.py:22:35: F821 undefined name 'Blog'
def fetch_blog(blog_id) -> Result['Blog', Exception]:
                                  ^
./betterpython/7 - dealing with errors/monadic-error-handling/example.py:41:27: F821 undefined name 'Blog'
def blog_to_dict(item) -> 'Blog':
                          ^
./betterpython/7 - dealing with errors/monadic-error-handling/example.py:52:28: F821 undefined name 'Blog'
def verify_access(blog) -> 'Blog':
                           ^
3     F821 undefined name 'Blog'
3