added new class

interface.py

@@ -1,7 +1,7 @@
 from transformers import AutoTokenizer, AutoModelForCausalLM
 from llama_index.core.llms import  CustomLLM, LLMMetadata, CompletionResponse, CompletionResponseGen
 from llama_index.core.llms.callbacks import llm_completion_callback
-from typing import Any
+from typing import Any, Iterator
 import torch
 from transformers import TextIteratorStreamer
 from threading import Thread