Find all unique combinations of a given length for an input of a given size

combinations.py

def find_combinations(input_size=3, output_size=3):
    return find_combinations_in_array(
        list(range(1, input_size+1)), [], [], output_size)


def find_combinations_in_array(remaining_digits, combinations, combination, combination_length):
    print('IN', remaining_digits, combination, combination, combination_length)
    # exit strategy
    # If the combination is already *combination_length* long
    if len(combination) == combination_length:
        print('LEN OK')
        combinations = [
            *combinations, combination] if combination not in combinations else combinations
        combination = []
        return combinations

    for (index, number) in enumerate(remaining_digits):
        combinations = find_combinations_in_array(
            remaining_digits[index+1:], combinations, [*combination, number], combination_length)
    return combinations
    print('OUT')


find_combinations()