System.Data.DataTableCollection.IndexOf C# (CSharp) Method

        internal int IndexOf(string tableName, string tableNamespace, bool chekforNull)
        {
            // this should be public! why it is missing?
            if (chekforNull)
            {
                if (tableName == null)
                {
                    throw ExceptionBuilder.ArgumentNull(nameof(tableName));
                }
                if (tableNamespace == null)
                {
                    throw ExceptionBuilder.ArgumentNull(nameof(tableNamespace));
                }
            }
            int index = InternalIndexOf(tableName, tableNamespace);
            return (index < 0) ? -1 : index;
        }