Methods in an intermediate state should be saved for each user

[gialmisi]

Right now, when a user starts a new interactive method, the old instance of the method is always replaced with the new one. This makes it impossible for a user to start one method, then utilize another method in the meantime, and then return to the first method and continue from where it left.

It can also be beneficial to store the method at each iteration for the user. If pickling works for this, then use pickles. If not, then something else should be devised.