@staticmethod
def is_feed_data(text: str, content_type: str) ->bool:
    """
        Return True if text string has valid feed beginning.

        :param text: Possible feed text
        :param content_type: MimeType of text
        :return: bool
        """
    data = text.lower()
    if not data:
        return False
    if data[:100].count('<html'):
        return False
    if 'json' in content_type and data.count('jsonfeed.org'):
        return True
    return bool(data.count('<rss') + data.count('<rdf') + data.count('<feed'))
