With --quiet activated, user interaction is disabled, i.e. no messages
are printed (except errors) and if login credentials are needed but not
given, instaloader fails.
We used to say in the project description text that we need Python>=3.2,
but I just noted that we use print() flush parameter, which was
introduced with python 3.3. Pylint would have warned that our code would
fail with Python 3.2.
Alexander Graf