docs: function getFirstViableCandidate(candidates) {
      for( const candidate of candidates) {
          const fileJS = `${candidate}.js`;
          if( Fs.existsSync(fileJS) ) return candidate;
          const fileXJS = `${candidate}.xjs`;
          if( Fs.existsSync(fileXJS) ) return candidate;
      }
  
      return candidates[0];
  }