Generating a Poem from Content Using Structured LLM

trying to run this code for structured output
from llama_index.core.llms import ChatMessage sllm = llm.as_structured_llm(output_cls=Content) input_msg = ChatMessage.from_str(f"Generate a poem from the content: {content}") response = sllm.chat(input_msg)

and getting this error
Input should be a valid dictionary or instance of ChatMessage
i checked the input_msg and it is a ChatMessage object