Question: 
Write a function to find all possible combinations of the elements of a given list.


Model's Code:
def combinations_list(elements):
    result = []
    n = len(elements)
    for i in range(1 << n):
        combination = [elements[j] for j in range(n) if (i & (1 << j))]
        result.append(combination)
    return result



Sample Correct Code:
def combinations_list(list1):
    if len(list1) == 0:
        return [[]]
    result = []
    for el in combinations_list(list1[1:]):
        result += [el, el+[list1[0]]]
    return result


Asserts:
assert combinations_list(['orange', 'red', 'green', 'blue'])==[[], ['orange'], ['red'], ['red', 'orange'], ['green'], ['green', 'orange'], ['green', 'red'], ['green', 'red', 'orange'], ['blue'], ['blue', 'orange'], ['blue', 'red'], ['blue', 'red', 'orange'], ['blue', 'green'], ['blue', 'green', 'orange'], ['blue', 'green', 'red'], ['blue', 'green', 'red', 'orange']]
assert combinations_list(['red', 'green', 'blue', 'white', 'black', 'orange'])==[[], ['red'], ['green'], ['green', 'red'], ['blue'], ['blue', 'red'], ['blue', 'green'], ['blue', 'green', 'red'], ['white'], ['white', 'red'], ['white', 'green'], ['white', 'green', 'red'], ['white', 'blue'], ['white', 'blue', 'red'], ['white', 'blue', 'green'], ['white', 'blue', 'green', 'red'], ['black'], ['black', 'red'], ['black', 'green'], ['black', 'green', 'red'], ['black', 'blue'], ['black', 'blue', 'red'], ['black', 'blue', 'green'], ['black', 'blue', 'green', 'red'], ['black', 'white'], ['black', 'white', 'red'], ['black', 'white', 'green'], ['black', 'white', 'green', 'red'], ['black', 'white', 'blue'], ['black', 'white', 'blue', 'red'], ['black', 'white', 'blue', 'green'], ['black', 'white', 'blue', 'green', 'red'], ['orange'], ['orange', 'red'], ['orange', 'green'], ['orange', 'green', 'red'], ['orange', 'blue'], ['orange', 'blue', 'red'], ['orange', 'blue', 'green'], ['orange', 'blue', 'green', 'red'], ['orange', 'white'], ['orange', 'white', 'red'], ['orange', 'white', 'green'], ['orange', 'white', 'green', 'red'], ['orange', 'white', 'blue'], ['orange', 'white', 'blue', 'red'], ['orange', 'white', 'blue', 'green'], ['orange', 'white', 'blue', 'green', 'red'], ['orange', 'black'], ['orange', 'black', 'red'], ['orange', 'black', 'green'], ['orange', 'black', 'green', 'red'], ['orange', 'black', 'blue'], ['orange', 'black', 'blue', 'red'], ['orange', 'black', 'blue', 'green'], ['orange', 'black', 'blue', 'green', 'red'], ['orange', 'black', 'white'], ['orange', 'black', 'white', 'red'], ['orange', 'black', 'white', 'green'], ['orange', 'black', 'white', 'green', 'red'], ['orange', 'black', 'white', 'blue'], ['orange', 'black', 'white', 'blue', 'red'], ['orange', 'black', 'white', 'blue', 'green'], ['orange', 'black', 'white', 'blue', 'green', 'red']]
assert combinations_list(['red', 'green', 'black', 'orange'])==[[], ['red'], ['green'], ['green', 'red'], ['black'], ['black', 'red'], ['black', 'green'], ['black', 'green', 'red'], ['orange'], ['orange', 'red'], ['orange', 'green'], ['orange', 'green', 'red'], ['orange', 'black'], ['orange', 'black', 'red'], ['orange', 'black', 'green'], ['orange', 'black', 'green', 'red']]


Tests:
Test 1 of 3: FAIL: AssertionError()

Test 462 of 974: 337/462 (72.94372294372295%): failed