Messages and Prints are just shown after the end of the evaluation.

[mmatera]

Suppose you are running a long calculus, and something happens in the middle (an error, or a message, or you are running a long simulation, and you want to tell the user at which step you are). With the current implementation, the user is going to be aware just after the run finishes, which could be never. It would be nice to improve the query function (https://github.com/Mathics3/mathics-django/blob/dfe9aeeecb31552f1c7f488547929658261dd928/mathics_django/web/views.py#L104), in a way that each time the evaluation receive a message, it be displayed 'online'.