'Check if a :attr:`text` is a valid SubRip format.
:return: whether or not the subtitle is valid.
:rtype: bool'

def is_valid(self):

    if (not self.text):
        return False
    try:
        pysrt.from_string(self.text, error_handling=pysrt.ERROR_RAISE)
    except pysrt.Error as e:
        if (e.args[0] < 80):
            return False
    return True
