public override string ToString()
{
StringBuilder sb = new StringBuilder("alter_partition_result(");
sb.Append("O1: ");
sb.Append(O1 == null ? "<null>" : O1.ToString());
sb.Append(",O2: ");
sb.Append(O2 == null ? "<null>" : O2.ToString());
sb.Append(")");
return sb.ToString();
}