    # File lib/fog/aws/cloud_watch.rb, line 53
            def initialize(options={})
              @aws_access_key_id = options[:aws_access_key_id]

              @region = options[:region] || 'us-east-1'

              unless ['ap-northeast-1', 'ap-southeast-1', 'eu-west-1', 'sa-east-1', 'us-east-1', 'us-west-1', 'us-west-2'].include?(@region)
                raise ArgumentError, "Unknown region: #{@region.inspect}"
              end
            end