Methods

[j.crater]

You already wrote two methods (init and str), although they are special class methods. But you proceed exactly the same way with writing your methods. Just give them proper names like mark_read() and is_long(), or anything you prefer.
I just stumbled upon this
https://www.python.org/dev/peps/pep-0008...-variables
you may use it to follow a naming convention for coding in Python.