InterlacedSmoothing-how to apply filter in this function

[SerbianBoss]

This is function from avisynth site:

This applies any filter to an interlaced source. 
The filter can be used for both spatial filters, like blur() and temporal filters like temporalsoften.

function ApplyInterlacedFilter(clip v1, string filter) {

    v2 = separatefields(v1) 
    selecteven(v2) 
    even = Eval(filter) 
    selectodd(v2) 
    odd = Eval(filter) 
    interleave(even,odd) 
    return weave() 

}

I try but i get error invalid argument to function Applyinterlaced filter. How to proper setup for example with degrainmedian filter