def check_abstraction():
    "\n    There's nothing for you to do for this function, it's just here for the extra doctest\n    >>> change_abstraction(True)\n    >>> city1 = make_city('city1', 0, 1)\n    >>> city2 = make_city('city2', 0, 2)\n    >>> distance(city1, city2)\n    1.0\n    >>> city3 = make_city('city3', 6.5, 12)\n    >>> city4 = make_city('city4', 2.5, 15)\n    >>> distance(city3, city4)\n    5.0\n    >>> berkeley = make_city('Berkeley', 37.87, 112.26)\n    >>> stanford = make_city('Stanford', 34.05, 118.25)\n    >>> closer_city(38.33, 121.44, berkeley, stanford)\n    'Stanford'\n    >>> bucharest = make_city('Bucharest', 44.43, 26.10)\n    >>> vienna = make_city('Vienna', 48.20, 16.37)\n    >>> closer_city(41.29, 174.78, bucharest, vienna)\n    'Bucharest'\n    >>> change_abstraction(False)\n    "
There's nothing for you to do for this function, it's just here for the extra doctest
>>> change_abstraction(True)
>>> city1 = make_city('city1', 0, 1)
>>> city2 = make_city('city2', 0, 2)
>>> distance(city1, city2)
1.0
>>> city3 = make_city('city3', 6.5, 12)
>>> city4 = make_city('city4', 2.5, 15)
>>> distance(city3, city4)
5.0
>>> berkeley = make_city('Berkeley', 37.87, 112.26)
>>> stanford = make_city('Stanford', 34.05, 118.25)
>>> closer_city(38.33, 121.44, berkeley, stanford)
'Stanford'
>>> bucharest = make_city('Bucharest', 44.43, 26.10)
>>> vienna = make_city('Vienna', 48.20, 16.37)
>>> closer_city(41.29, 174.78, bucharest, vienna)
'Bucharest'
>>> change_abstraction(False)
def check_abstraction():
    "\n    There's nothing for you to do for this function, it's just here for the extra doctest\n    >>> change_abstraction(True)\n    >>> city1 = make_city('city1', 0, 1)\n    >>> city2 = make_city('city2', 0, 2)\n    >>> distance(city1, city2)\n    1.0\n    >>> city3 = make_city('city3', 6.5, 12)\n    >>> city4 = make_city('city4', 2.5, 15)\n    >>> distance(city3, city4)\n    5.0\n    >>> berkeley = make_city('Berkeley', 37.87, 112.26)\n    >>> stanford = make_city('Stanford', 34.05, 118.25)\n    >>> closer_city(38.33, 121.44, berkeley, stanford)\n    'Stanford'\n    >>> bucharest = make_city('Bucharest', 44.43, 26.10)\n    >>> vienna = make_city('Vienna', 48.20, 16.37)\n    >>> closer_city(41.29, 174.78, bucharest, vienna)\n    'Bucharest'\n    >>> change_abstraction(False)\n    "