auto x = symbol("x");                                                                                                                                                  
auto y = symbol("y");                                                                                                                                                  
auto i2 = integer(2);                                                                                                                                                  
// test cse within piecewise                                                                                                                                           
auto pw1 = piecewise({                                                                                                                                                 
    {pow(add(x, y), i2), Gt(x, y)},                                                                                                                                    
    {sqrt(add(x, y)), boolTrue}                                                                                                                                        
});                                                                                                                                                                    
                                                                                                                                                                       
vec_pair substs;                                                                                                                                                       
vec_basic reduced;                                                                                                                                                     
cse(substs, reduced, {pw1});                                                                                                                                           
std::cout << "substs.size() = " << substs.size() << std::endl;