What does the second argument of the Session.pop method do in Python Flask?
According to Flask's API their Session class is a wrapper around a python Dict. According to the python documentation for dict.pop():
pop(key[, default])If
keyis in the dictionary, remove it and return its value, else returndefault. Ifdefaultis not given andkeyis not in the dictionary, aKeyErroris raised.
In this case the tutorial asks you to pass in None as the default value.