# Substitution of a list of variables

I wish substituting a list of variables, without having to substitute them 1 by 1.

Here is an example with an attempt which doesn't work :

```
sage: V=[var('x_%d' % i) for i in range(10)]; V
[x_0, x_1, x_2, x_3, x_4, x_5, x_6, x_7, x_8, x_9]
sage: S=[sum(V),prod(V)]; S
[x_0 + x_1 + x_2 + x_3 + x_4 + x_5 + x_6 + x_7 + x_8 + x_9,
x_0*x_1*x_2*x_3*x_4*x_5*x_6*x_7*x_8*x_9]
sage: for i in range(10):
....: S.subs(V[i]=i)
....:
File "<ipython-input-99-7670392e3358>", line 2
SyntaxError: keyword can't be an expression
```

How can we do this ?