def is_positive_int(arg):
    """
    Determines if the argument is an integer greater than zero

    :param arg: A string to be evaluate as a positive integer
    :type arg: types.str

    :return: A boolean indicator True or False
    :rtype:  bool

    :author: Milica Ng
    """
    if not isinstance(arg, int):
        return False
    elif not arg > 0:
        return False
    else:
        return True
