def isupper(text):
    """
    Checks if all cased characters in ``text`` are uppercase and there is at least one cased character.
    
    Cased characters are defined by the Unicode standard.  All alphabetic characters in the
    ASCII character set are cased.
    
    :param text: The string to check
    :type text:  ``str``
    
    :return: True if all cased characters in ``text`` are uppercase and there is at least one cased character, False otherwise.
    :rtype:  ``bool``
    """
    assert isinstance(text, str), '%s is not a string' % text
    return text.isupper()
