code: def find_rt_jar(javahome=None):
      
  
      if not javahome:
          if 'JAVA_HOME' in os.environ:
              javahome = os.environ['JAVA_HOME']
          elif sys.platform == 'darwin':
              # The default java binary on OS X is not part of a standard Oracle
              # install, so building paths relative to it does not work like it
              # does on other platforms.
              javahome = _find_osx_javahome()
          else:
              javahome = _get_javahome_from_java(_find_java_binary())
  
      rtpath = os.path.join(javahome, 'jre', 'lib', 'rt.jar')
      if not os.path.isfile(rtpath):
          msg = 'Could not find rt.jar: {} is not a file'.format(rtpath)
          raise ExtensionError(msg)
  
      return rtpath
docs: Find the path to the Java standard library jar.
  
      The jar is expected to exist at the path 'jre/lib/rt.jar' inside a
      standard Java installation directory. The directory is found using
      the following procedure:
  
      1. If the javehome argument is provided, use the value as the
         directory.
      2. If the JAVA_HOME environment variable is set, use the value as
         the directory.
      3. Find the location of the ``java`` binary in the current PATH and
         compute the installation directory from this location.
  
      Args:
          javahome: A path to a Java installation directory (optional).