Update langdemo.py

Update prompting in the langchain demo to follow the V2 convention.

langdemo.py

@@ -69,9 +69,10 @@ def cylinder_volume(radius, height):
 
 RAVEN_PROMPT = """
 {raven_tools}
-User Query: Question: {input}
+User Query: {input}<human_end>
+
+"""
 
-Please pick a function from the above options that best answers the user query and fill in the appropriate arguments.<human_end>"""
 
 
 # Set up a prompt template
@@ -82,10 +83,10 @@ class RavenPromptTemplate(StringPromptTemplate):
     tools: List[Tool]
 
     def format(self, **kwargs) -> str:
-        prompt = "<human>:\n"
+        prompt = ""
         for tool in self.tools:
             func_signature, func_docstring = tool.description.split(" - ", 1)
-            prompt += f'\nOPTION:\n<func_start>def {func_signature}<func_end>\n<docstring_start>\n"""\n{func_docstring}\n"""\n<docstring_end>\n'
+            prompt += f'\nFunction:\ndef {func_signature}\n"""\n{func_docstring}\n"""\n'
         kwargs["raven_tools"] = prompt
         return self.template.format(**kwargs).replace("{{", "{").replace("}}", "}")