<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def datetime_timezone(tz):
 """ This method given a timezone returns a localized datetime object. """

    utc_datetime_naive = datetime.utcnow()
    # return a localized datetime to UTC
    utc_localized_datetime = localize(utc_datetime_naive, 'UTC')
    # normalize the datetime to given timezone
    normalized_datetime = normalize(utc_localized_datetime, tz)
    return normalized_datetime