get_combinations.py

def get_combinations(input: list) -> list:
    """
    get_combinations() can be used to find all possible combinations of a
    flat list of values.
    """

    # start with a non-empty payload just to get the initial for loop going
    combinations = [[]]

    # iterate over every value once
    for x in input:
        curr = []

        # take previous combos and add current value, generating a new combo
        for combination in combinations:
            curr += [combination + [x]]

        combinations += curr

    # trim out the initial payload so we only get non-empty results
    return combinations[1:]

result = get_combinations([0, 3, 6, 9])

"""
result when sorted:

[
  [0],
  [0, 3],
  [0, 3, 6],
  [0, 3, 6, 9],
  [0, 3, 9],
  [0, 6],
  [0, 6, 9],
  [0, 9],
  [3],
  [3, 6],
  [3, 6, 9],
  [3, 9],
  [6],
  [6, 9],
  [9]
]
"""