code: public ClassFile find(String className) {
          for (PathEntry pe : list) {
              ClassFile cf = pe.find(className);
              if (cf != null) {
                  return cf;
              }
          }
          return null;
      }
docs: Searches the class path for a class with the given name,
  returning a ClassFile for it. Returns null if not found.
  
  @param className the class to search for
  @return a ClassFile instance, or null if not found