from datetime import datetime


def today_datetime(utc_now):
    """ This function returns the datetime limits for a given UTC datetime
        @parameters
            utc_now         (datetime)  the datetime to be based on
        @returns
            today_start:    (datetime)  the first moment of current day
            today_end:      (datetime)  the last moment of current day
    """

    today_start = datetime(utc_now.year, utc_now.month, utc_now.day, 0, 0, 0)
    today_end = datetime(utc_now.year, utc_now.month, utc_now.day, 23, 59, 59)

    return today_start, today_end

    # -----------------------------------------------------------------------------------------------------------------#