### Restriction of scalars for free modules

Suppose I have a free module `M`

over `QQ[x]`

. How do I obtain the underlying `QQ`

vector space? FreeModule does not have this coercion:

```
sage: R = PolynomialRing(QQ,'x')
sage: R in CommutativeAlgebras(QQ)
True
sage: M = FreeModule(R,3)
sage: M in VectorSpaces(QQ)
False
```

And `CombinatorialFreeModule`

only takes already subcategories of `QQ`

-vector spaces:

```
sage: M = CombinatorialFreeModule(QQ, ['a','b','c'], category=Modules(R))
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
....
ValueError: Subcategory of `Category of vector spaces with basis over Rational Field` required; got `Category of modules over Univariate Polynomial Ring in x over Rational Field`
```