code: public synchronized EvaluatorContext getContext(final String contextId) {
      for (final EvaluatorContext context : this.contextStack) {
        if (context.getId().equals(contextId)) {
          return context;
        }
      }
      throw new RuntimeException("Unknown evaluator context " + contextId);
    }
docs: Fetch the context with the given ID.
  
  @param contextId
  @return