client = boto3.client('rds', region_name=region)
source_snaps = client.describe_db_cluster_snapshots(DBClusterIdentifier = 'main-production')['DBClusterSnapshots']
source_snap = sorted(source_snaps, key=byTimestamp, reverse=True)[0]['DBClusterSnapshotIdentifier']

response = client.restore_db_cluster_from_snapshot(
  DBClusterIdentifier='main-development',
  SnapshotIdentifier=source_snap,
  Port=port,
  Engine='aurora-postgresql')

i = client.create_db_instance(
  DBName='main',
  DBInstanceIdentifier='main-development',
  DBInstanceClass='db.r4.large',
  Engine='aurora-postgresql',
  MasterUsername='mab_admin',
  MasterUserPassword='mypassword',
  AllocatedStorage=20,
  DBClusterIdentifier='main-development')