How do I assign the same value to every field, including nested fields of a structure?

Say I have a structure which has an unknown number of fields and each field may or may not have subfields. I want to assign a certain value to each field value. I would be okay only going two fields deep into the structure.

For example: Let A have fields a,b, and field a has fields c,d, but field b has no fields. I want to assign all fields to be x so that the result is

A.a.c = x;
A.a.d = x;
A.b = x;

Answer 1

[Walter Roberson]

   A = structfun(@(s) layer2(s,x), 'Uniform', 0);

together with

   function r = layer2(s, x)
     if istruct(s)
       fn = fieldnames(s);
       r = cell2struct( repmat({x}, length(fn), 1), fn, 1);
     else
       r = x;
     end
  end