code: function (data, id, context) {
              var glob = this.getPreferenceLocation(data, id, context);
  
              if (!glob) {
                  return;
              }
  
              return data[glob][id];
          }
docs: Retrieve the current value based on the filename in the context
  object, comparing globs relative to the prefFilePath that this
  PathLayer was set up with.
  
  @param {Object} data the preference data from the Scope
  @param {string} id preference ID to look up
  @param {Object} context Object with filename that will be compared to the globs