fCraft.Drawing.DrawOperation.TestForDuplicateModification C# (CSharp) Method

        void TestForDuplicateModification()
        {
            int index = Map.Index( Coords );
            if( modifiedBlockIndices.Contains( index ) ) {
                throw new InvalidOperationException( "Duplicate block modification at " + Coords );
            }
            modifiedBlockIndices.Add( index );
        }