docs: @Override
      public boolean apply( String inputKey, Optional<Object> inputOptional, WalkedPath walkedPath, Map<String,Object> output, Map<String, Object> context){
  
          Object input = inputOptional.get();
          MatchedElement thisLevel = pathElement.match( inputKey, walkedPath );
          if ( thisLevel == null ) {
              return false;
          }
  
          Object data;
          boolean realChild = false;  // by default don't block further Shiftr matches
  
          if ( this.pathElement instanceof DollarPathElement ||
               this.pathElement instanceof HashPathElement ) {
  
              // The data is already encoded in the thisLevel object created by the pathElement.match called above
              data = thisLevel.getCanonicalForm();
          }
          else if ( this.pathElement instanceof AtPathElement ) {
  
              // The data is our parent's data
              data = input;
          }
          else if ( this.pathElement instanceof TransposePathElement ) {
              // We try to walk down the tree to find the value / data we want
              TransposePathElement tpe = (TransposePathElement) this.pathElement;
  
              // Note the data found may not be a String, thus we have to call the special objectEvaluate
              Optional<Object> evaledData = tpe.objectEvaluate( walkedPath );
              if ( evaledData.isPresent() ) {
                  data = evaledData.get();
              }
              else {
                  // if we could not find the value we want looking down the tree, bail
                  return false;
              }
          }
          else {
              // the data is the input
              data = input;
              // tell our parent that we matched and no further processing for this inputKey should be done
              realChild = true;
          }
  
          // Add our the LiteralPathElement for this level, so that write path References can use it as &(0,0)
          walkedPath.add( input, thisLevel );
  
          // Write out the data
          for ( PathEvaluatingTraversal outputPath : shiftrWriters ) {
              outputPath.write( data, output, walkedPath );
          }
  
          walkedPath.removeLast();
  
          if ( realChild ) {
              // we were a "real" child, so increment the matchCount of our parent
              walkedPath.lastElement().getMatchedElement().incrementHashCount();
          }
  
          return realChild;
      }