### Defining a function of the form $f(x_1,x_2,...,x_n)=\sum_{i=0}^n x_i$
How can I define a function of the form $$f(x_1,x_2,...,x_n)=\sum_{i=0}^n x_i$$ I tried the following
sage: n = 2
sage: x = [ var('x_%d' % i) for i in range(n) ]
sage: f(x)=sum(x[i],i,0,n)