@staticmethod
def label_gen(limit: int=None) ->str:
    """generates a sequential headers. if limit is set will return at that limit"""
    headers = list('ABCDEFGHIJKLMNOPQRSTUVWXYZ')
    counter = 0
    for n in range(0, 100):
        for i in range(len(headers)):
            rtn_str = f'{headers[i]}' if n == 0 else f'{headers[i]}{n}'
            if isinstance(limit, int) and counter >= limit:
                return rtn_str
            counter += 1
            yield rtn_str
