code: public Mat4 add(final Mat4 other) {
              return new Mat4(
                              m00 + other.m00, m01 + other.m01, m02 + other.m02, m03 + other.m03,
                              m10 + other.m10, m11 + other.m11, m12 + other.m12, m13 + other.m13,
                              m20 + other.m20, m21 + other.m21, m22 + other.m22, m23 + other.m23,
                              m30 + other.m30, m31 + other.m31, m32 + other.m32, m33 + other.m33
              );
          }
docs: Add two matrices together and return the result
  @param other