fCraft.PrepareParametrizedManifold.CheckCoordVar C# (CSharp) Method

        private static void CheckCoordVar( string s )
        {
            if ( string.IsNullOrWhiteSpace( s ) || ( s != "x" && s != "y" && s != "z" ) )
                throw new ArgumentException( "expected assignment of x, y, or z (e.g. x=2*t)" );
        }