Is there a way to somehow conveniently take out the total numerical factor, because factor_out does not work for me. For example:

```
{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,q,r,s,u,v,w#}::Indices(full, values={t,x,y,z}, position=independent).
{t, x, y, z}::Coordinate.
ex:= -\frac{1}{4} A_{x} + -\frac{1}{4}A_{y};
factor_out(ex, $-\frac{1}{4}$);
```

does nothing