result += check_equal_simplify(e, 16 * color_ONE() / 9);
e = color_T(a) * color_T(b) * color_T(c) * color_T(c) * color_T(b) * color_T(a);
result += check_equal_simplify(e, 64 * color_ONE() / 27);
+ e = color_T(a) * color_T(b) * color_T(c) * color_T(k) * color_T(a) * color_T(k) * color_T(c) * color_T(b);
+ result += check_equal_simplify(e, -color_ONE() / 162);
return result;
}