code: def time_zone_by_country_and_region(country_code, region_code=None):
      
      timezone = country_dict.get(country_code)
      if not timezone:
          return None
  
      if isinstance(timezone, str):
          return timezone
  
      return timezone.get(region_code)
docs: Returns time zone from country and region code.
  
      :arg country_code: Country code
      :arg region_code: Region code