How to encode $$ variable for calling in custom function

Hi,
I want to get tmdbid of movie based on name+year through custom function call in xml scraper.

I have problem with missing html encode, which would format my $$ variable before tmdb call which using it. Without that, it works fine for simple one word movie titles, but even space of course destroys the call, because it needs to be %20.

$$8 - GetSearchResults
$$7 - movie title in plaintext from previous GetDetails
$$16 - movie year from previous GetDetails

<RegExp input="$$7" output="https://api.themoviedb.org/3/search/movie?api_key=<api_key>&amp;amp;query=\1&amp;amp;year=$$16&amp;amp;language=en;" dest="11">

  <expression noclean="1"/>

</RegExp>



<RegExp input="$$11" output="&lt;url function=&quot;CustomFunction&quot;&gt;\1&lt;/url&gt;" dest="8+">

  <expression noclean="1"/>

</RegExp>    



<CustomFunction dest="13">

  <!-- tmdb id -->

  <RegExp input="$$1" output="\1" dest="5">

    <expression repeat="yes">&quot;id&quot;[0-9]*)</expression>

  </RegExp>

  ...

  ...        

</CustomFunction>