code: private AbstractTransform getTransform(String fileName) {
          File file = new File(fileName);
          
          for (Transform transform : transforms) {
              if (transform.filter.accept(file)) {
                  return transform.transform;
              }
          }
          
          return null;
      }
docs: Returns the transform for the file, or null if none registered.
  
  @param fileName The file name.
  @return The associated transform, or null if not found.