docs: def get_timezone_converter(from_timezone, to_tz=None, tz_aware=False):
      '''
      return a function that converts a given
      datetime object from a timezone to utc
  
      :param from_timezone: timezone name as string
      '''
      if not from_timezone:
          return None
      is_true(HAS_DATEUTIL, "`pip install python_dateutil` required")
      is_true(HAS_PYTZ, "`pip install pytz` required")
      from_tz = pytz.timezone(from_timezone)
      return partial(_get_timezone_converter, from_tz=from_tz, to_tz=to_tz,
                     tz_aware=tz_aware)