class Aws::Partitions::PartitionList

def build_metadata_regions(partition_name, metadata_regions, existing = nil)
  metadata_regions.each_with_object({}) do |(region_name, region), regions|
    if existing && existing.region?(region_name)
      regions[region_name] = existing.region(region_name)
    else
      regions[region_name] = Region.new(
        name: region_name,
        description: region['description'],
        partition_name: partition_name,
        services: Set.new
      )
    end
  end
end