The constant is only used in the VersionOne service and an empty string serves just as well. If an empty string were passed in this parameter previously you'd get an exception, so we aren't masking any useful behavior:
>>> pytz.timezone('')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "python3.10/site-packages/pytz/__init__.py", line 188, in timezone
raise UnknownTimeZoneError(zone)
pytz.exceptions.UnknownTimeZoneError: ''
The constant is only used in the VersionOne service and an empty string serves just as well. If an empty string were passed in this parameter previously you'd get an exception, so we aren't masking any useful behavior: