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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def make_sure_dir_exists(dir_, create_subfolders=False):
 """Ensures that a directory exists. Adapted from StackOverflow users "Bengt" and "Heikki Toivonen" (http://stackoverflow.com/a/5032238). Parameters dir_: str The directory path. create_subfolders: bool, optional Whether to create any inexistent subfolders. [False] Returns ------- None Raises ------ OSError If a file system error occurs. """

    assert isinstance(dir_, (str, _oldstr))
    assert isinstance(create_subfolders, bool)

    try:
        if create_subfolders:
            os.makedirs(dir_)
        else:
            os.mkdir(dir_)
    except OSError as exception:
        if exception.errno != errno.EEXIST:
            raise