                                                           ]
         )
         
-        // All values should match the input using subscripting
         XCTAssertEqual(matrix[.INTERIOR, .INTERIOR], Dimension.EMPTY)
         XCTAssertEqual(matrix[.INTERIOR, .BOUNDARY], Dimension.ZERO)
         XCTAssertEqual(matrix[.INTERIOR, .EXTERIOR], Dimension.ONE)

                                                          [.ONE,   .TWO,   .EMPTY],
                                                          ]
        )
        // All elements should match input
        XCTAssertEqual(matrix[.INTERIOR, .INTERIOR], Dimension.EMPTY)
        XCTAssertEqual(matrix[.INTERIOR, .BOUNDARY], Dimension.ZERO)
        XCTAssertEqual(matrix[.INTERIOR, .EXTERIOR], Dimension.ONE)

        
        var index: Int = 0
        
        for value in matrix {
            XCTAssertEqual(value, expectedValues[index])
            index += 1
