def assert_size!(matrix_width, matrix_height)
      if width != matrix_width
        raise ChunkyPNG::ExpectationFailed,
          "The width of the matrix does not match the canvas width!"
      end
      if height != matrix_height
        raise ChunkyPNG::ExpectationFailed,
          "The height of the matrix does not match the canvas height!"
      end
      true
    end
def assert_size!(matrix_width, matrix_height)
      if width != matrix_width
        raise ChunkyPNG::ExpectationFailed,
          "The width of the matrix does not match the canvas width!"
      end
      if height != matrix_height
        raise ChunkyPNG::ExpectationFailed,
          "The height of the matrix does not match the canvas height!"
      end
      true
    end
Throws an exception if the matrix width and height does not match this canvas' dimensions.