Fixed Regular expression (#2933)

###  https://github.com/hwchase17/langchain/issues/2898
Instead of `"Action" and "Action Input"` keywords, we are getting
`"Action 1" and "Action 1 Input" or "Action Input 1" ` from
**gpt-3.5-turbo**

 Updated the Regular expression to handle all these cases
 
Attaching the screenshot of the result from the updated Regular
expression.
 
<img width="1036" alt="Screenshot 2023-04-16 at 1 39 00 AM"
src="https://user-images.githubusercontent.com/55012400/232251184-23ca6cc2-7229-411a-b6e1-53b2f5ec18a5.png">

docs/modules/agents/agents/custom_agent_with_tool_retrieval.ipynb

@@ -315,7 +315,7 @@
     "                log=llm_output,\n",
     "            )\n",
     "        # Parse out the action and action input\n",
-    "        regex = r\"Action: (.*?)[\\n]*Action Input:[\\s]*(.*)\"\n",
+    "        regex = r\"Action\\s*\\d*\\s*:(.*?)\\nAction\\s*\\d*\\s*Input\\s*\\d*\\s*:[\\s]*(.*)\"\n",
     "        match = re.search(regex, llm_output, re.DOTALL)\n",
     "        if not match:\n",
     "            raise ValueError(f\"Could not parse LLM output: `{llm_output}`\")\n",

docs/modules/agents/agents/custom_llm_agent.ipynb

@@ -204,7 +204,7 @@
     "                log=llm_output,\n",
     "            )\n",
     "        # Parse out the action and action input\n",
-    "        regex = r\"Action: (.*?)[\\n]*Action Input:[\\s]*(.*)\"\n",
+    "        regex = r\"Action\\s*\\d*\\s*:(.*?)\\nAction\\s*\\d*\\s*Input\\s*\\d*\\s*:[\\s]*(.*)\"\n",
     "        match = re.search(regex, llm_output, re.DOTALL)\n",
     "        if not match:\n",
     "            raise ValueError(f\"Could not parse LLM output: `{llm_output}`\")\n",

docs/modules/agents/agents/custom_llm_chat_agent.ipynb

@@ -206,7 +206,7 @@
     "                log=llm_output,\n",
     "            )\n",
     "        # Parse out the action and action input\n",
-    "        regex = r\"Action: (.*?)[\\n]*Action Input:[\\s]*(.*)\"\n",
+    "        regex = r\"Action\\s*\\d*\\s*:(.*?)\\nAction\\s*\\d*\\s*Input\\s*\\d*\\s*:[\\s]*(.*)\"\n",
     "        match = re.search(regex, llm_output, re.DOTALL)\n",
     "        if not match:\n",
     "            raise ValueError(f\"Could not parse LLM output: `{llm_output}`\")\n",

docs/use_cases/agents/custom_agent_with_plugin_retrieval.ipynb

@@ -375,7 +375,7 @@
     "                log=llm_output,\n",
     "            )\n",
     "        # Parse out the action and action input\n",
-    "        regex = r\"Action: (.*?)[\\n]*Action Input:[\\s]*(.*)\"\n",
+    "        regex = r\"Action\\s*\\d*\\s*:(.*?)\\nAction\\s*\\d*\\s*Input\\s*\\d*\\s*:[\\s]*(.*)\"\n",
     "        match = re.search(regex, llm_output, re.DOTALL)\n",
     "        if not match:\n",
     "            raise ValueError(f\"Could not parse LLM output: `{llm_output}`\")\n",

langchain/agents/mrkl/base.py

@@ -42,7 +42,7 @@ def get_action_and_input(llm_output: str) -> Tuple[str, str]:
     if FINAL_ANSWER_ACTION in llm_output:
         return "Final Answer", llm_output.split(FINAL_ANSWER_ACTION)[-1].strip()
     # \s matches against tab/newline/whitespace
-    regex = r"Action: (.*?)[\n]*Action Input:[\s]*(.*)"
+    regex = r"Action\s*\d*\s*:(.*?)\nAction\s*\d*\s*Input\s*\d*\s*:[\s]*(.*)"
     match = re.search(regex, llm_output, re.DOTALL)
     if not match:
         raise ValueError(f"Could not parse LLM output: `{llm_output}`")