code: def extract_class(jar, name):
      
  
      with jar.open(name) as entry:
          return LinkableClass(javatools.unpack_class(entry))
docs: Extracts a LinkableClass from a jar.
  
      Args:
          jar: An open ZipFile instance.
          name: A string containing the binary name of a class.
  
      Raises:
          KeyError: The class does not exist in the jar.