Count the number of indirectly used assemblies in NDepend

I'm trying to count the indirect assembly references. The following does not work because IsIndirectlyUsing wants a constant string: "Only constant literal string are accepted as input for IsIndirectlyUsing(string)"

Is there a method to get the indirect assemblies used?

from a in Assemblies 

let indirectlyUsed = 
  from dep in Assemblies
  let depName = a.FullName
  where a.IsIndirectlyUsing(depName)
  select dep

where a.PDBFound orderby a.AssembliesUsed.Count() descending
select new { a, a.AssembliesUsed, indirectlyUsed, a.NbLinesOfCode, a.NbILInstructions }```

The NDepend.API method FillIterative() is here to help:

from a in Assemblies 

let indirectlyUsed = a.AssembliesUsed.FillIterative(
    asms => asms.SelectMany(a1 => a1.AssembliesUsed)).DefinitionDomain

where a.PDBFound orderby indirectlyUsed .Count() descending
select new { a, a.AssembliesUsed, indirectlyUsed, a.NbLinesOfCode, a.NbILInstructions }