### general implicit differentiation

Recently i have ~~beenhelped ~~been helped to write an implicit function differentiator (nice neologism isn't it). Here is the code

```
def implicit_derivative(V):
var("dw1, dw2")
V_w1 = diff(V, w1)
V_w2 = diff(V, w2)
# Differential
dV = V_w1 * dw1 + V_w2 * dw2
# Dérivée du premier ordre
sol=solve(dV==0, dw2)
impder=(sol[0]/dw1)
return impder
```

This work without difficulty for $V$ function of $w_1$ and $w_2$. But if my variables are $x$ and $y$ or say $\chi$ and $\zeta$. It will not work. I have not ~~ound ~~found the mechanism to define a general function not dependant of the name of its arguments. And here there is a second problem to find thway to associate the increase d. to it correlative argument that is if I use $\chi$ as the first variable $d\chi$must substitute to $dw_1$.