Fix undefined names in Python code

[cclauss]

% flake8 . --count --builtins=ml_ops --select=E9,F63,F7,F82,Y --show-source --statistics

./pyze/src/pyze/api/kamereon.py:31:13: F821 undefined name 'f'
            f.cache_clear()
            ^
./pyze/src/pyze/api/kamereon.py:326:113: F821 undefined name 'schedule'
            raise RuntimeError('Expected schedule to be instance of ChargeSchedules, but got {} instead'.format(schedule.__class__))
                                                                                                                ^
2     F821 undefined name 'f'
2