How do I define two mutually dependent parameters in Python?

I want to create a Python class with two mutually inclusive parameters that are dependent on each other. The user must either provide a value for both parameters or neither. If one parameter is specified without the other, an exception should be raised.

class TestEvent:
    def __init__(self, start_date = None, end_date = None , **kwargs):
        # Check if start_date and end_date are defined 
        pass

valid_event_1 = TestEvent()
valid_event_2 = TestEvent(start_date = '2022-07-01', end_date = '2022-08-01')
invalid_event_1 = TestEvent(start_date = '2022-07-01')  # Raise exception
invalid_event_2 = TestEvent(end_date = '2022-08-01')  # Raise exception

How can I define two mutually dependent parameters in Python?

You could express the mutual exclusive ^-operator.

if (start_date is None) ^ (end_date is None):
   print('Error')

Here the table of values for the ^-operator

from itertools import product

def xor_table_of_values():
    """
      1   ^   1   -> 0
      1   ^   0   -> 1
      0   ^   1   -> 1
      0   ^   0   -> 0
    """
    print(*(f'{i:^5} ^ {j:^5} -> {int(i^j)}' for i, j in product((True, False), repeat=2)), sep='\n')

xor_table_of_values()

Here a (verbose) abstraction:

def test(start_date=None, end_date=None):

    is_given_sd = start_date is not None
    is_given_ed = end_date is not None

    if is_given_sd ^ is_given_ed:
        print('Error')


test(start_date='7', end_date='767')
#
test(start_date='2')
# Error
test(end_date='43')
# Error
test()
#