from datetime import datetime
import pytz


def timezone_date(tz='Asia/Shanghai'):
    """ return current date object by timezone
    Args:
        tz (str): one of timezone from pytz.all_timezones
    Returns:
        datetime (datetime.datetime): datetime object
    """
    utcmoment_unaware = datetime.utcnow()
    utcmoment = utcmoment_unaware.replace(tzinfo=pytz.utc)
    local_datetime = utcmoment.astimezone(pytz.timezone(tz))
    return local_datetime