I am following the tutorial on transient Stokes solver. In the last code snippet, I find the following line:

`w1[]=sol; u=w1; v= w2; p=wp;`

which saves the solution from `w1[]`

corresponding to a `P2,P2,P1`

mixed space to individual variables `u`

,`v`

,`p`

corresponding to spaces in `P2`

,`P2`

,`P1`

respectively.

I want to do the opposite of it where I have variables in individual spaces and convert them to a combined mixed element space. I want to achieve this so that it becomes easier to write the data using `ofstream`

and access it in another code.

Thanks.