def _is_abbreviation(tuple):
    """
    Checks if value can be interpreted as an abbreviation (thus, not a compound word)

    :param tuple: the value as tuple, (is_upper_case_flag, value)
    :return: boolean True or False, if value was determined as abbreviation or not
    """

    # example tuple[1].isupper(): ARD
    # example (tuple[1][0].islower() and tuple[1][-1].isupper()): mA
    # example (len(tuple[1])==2 and tuple[1][0].isupper() and tuple[1][1].islower()): Mi, St
    return tuple[1].isupper() \
           or (tuple[1][0].islower() and tuple[1][-1].isupper()) \
           or (len(tuple[1]) == 2 and tuple[1][0].isupper() and tuple[1][1].islower())