# Defining a function of vector variables

I would like to define a Sage function that takes a vector variable and computes the result of some vector function on it, something like

```
f(v) = v.dot_product(vector((1,1)))
```

However, when I try to run this in Sage, I get

```
AttributeError: 'sage.symbolic.expression.Expression' object has no
attribute 'dot_product'
```

Is there a way to achieve this effect in Sage?

To elaborate, `f(v)` creates a symbolic variable `v`, which is not (necessarily) a vector. Sage doesn't currently have symbolic vector types per se.