Adding type hints

[mo1ein]

Hi!
I think it's better to use typing hints. That makes code cleaner. See PEP 484.
For example, this part:

def transform_numeral_date(data):
    # for example '1397/12/6' or 2018-2-25 which is my birthday :)
    if data.find('/') != -1:
        _type = 'solar'
    else: # assume gregorian
        _type = 'gregorian'
    data = data.strip().replace('/', '-').split('-')
    (year, month, day) = (transform_number(data[0])
                         ,transform_number(data[1])
                         ,transform_number(data[2]))
    season = find_season(int(month), _type)
    return (year, season, month, day)

Converts to:

from typing import Tuple
def transform_numeral_date(data: str) -> Tuple[int, Tuple[str, int], int, int]:
    # for example '1397/12/6' or 2018-2-25 which is my birthday :)
    if data.find('/') != -1:
        _type = 'solar'
    else: # assume gregorian
        _type = 'gregorian'
    data = data.strip().replace('/', '-').split('-')
    (year, month, day) = (transform_number(data[0])
                         ,transform_number(data[1])
                         ,transform_number(data[2]))
    season = find_season(int(month), _type)
    return (year, season, month, day)

If you think that's OK, I can fix it.