You can add logging code to a library like in this excample:

{% include file="examples/python/loglib/lib.py" %}

and it will not bother the person who uses the library without enabling any logging like this code:

{% include file="examples/python/loglib/use_without.py" %}

The output will look like this:

$ python examples/python/loglib/use_without.py
before
after

If the user enabled logging, then that logging will be also included.

{% include file="examples/python/loglib/use_with.py" %}

$ python examples/python/loglib/use_with.py
before
DEBUG:root:hello
after