def _(): assert bf.determine_mode([1, 2.0, '3']) == 'mixed'
def _(): assert bf.determine_mode(['1', '2', '3']) == 'str'
def _(): assert bf.determine_mode([1, 2, 3]) == 'int'
def _(): assert bf.determine_mode([1.0, 2.0, 3.0]) == 'float'
def _(): assert bf.determine_mode([]) is None