const awsS3Endpoint = {
  'us-east-1': 's3.amazonaws.com',
  'us-east-2': 's3-us-east-2.amazonaws.com',
  'us-west-1': 's3-us-west-1.amazonaws.com',
  'us-west-2': 's3-us-west-2.amazonaws.com',
  'ca-central-1': 's3.ca-central-1.amazonaws.com',
  'eu-west-1': 's3-eu-west-1.amazonaws.com',
  'eu-west-2': 's3-eu-west-2.amazonaws.com',
  'sa-east-1': 's3-sa-east-1.amazonaws.com',
  'eu-central-1': 's3-eu-central-1.amazonaws.com',
  'ap-south-1': 's3-ap-south-1.amazonaws.com',
  'ap-southeast-1': 's3-ap-southeast-1.amazonaws.com',
  'ap-southeast-2': 's3-ap-southeast-2.amazonaws.com',
  'ap-northeast-1': 's3-ap-northeast-1.amazonaws.com',
  'cn-north-1': 's3.cn-north-1.amazonaws.com.cn'
};

// getS3Endpoint get relevant endpoint for the region.
String getS3Endpoint(String region) {
  assert(region != null);
  final endpoint = awsS3Endpoint[region];
  return endpoint ?? 's3.amazonaws.com';
}