# convert integrate() to ds();


todiff(integrates(f_,x_,a_,b_)):=ds(x=>f,x,a,b);
todiff(integrates(f_,x_)):=ds(x=>f,x,-1);
todiff(integrate(f_,x_)):=ds(x=>f,x,-1);
todiff(d(f_,x_)):=ds(x=>f,x);
todiff(d(f_,x_,n_)):=ds(x=>f,x,n);

todiff(f_+g_):=todiff(f_)+todiff(g_);
todiff(f_*g_):=todiff(f_)*todiff(g_);