if input_mapper:
        prompt_input = input_mapper(first_example.inputs)
        if not isinstance(prompt_input, str) and not (
            isinstance(prompt_input, list)
            and all(isinstance(msg, BaseMessage) for msg in prompt_input)
        ):
            raise InputFormatError(
                "When using an input_mapper to prepare dataset example inputs"
                " for an LLM or chat model, the output must a single string or"
                " a list of chat messages."
                f"\nGot: {prompt_input} of type {type(prompt_input)}."
            )
    else:
        try:
            _get_prompt(first_example.inputs)
        except InputFormatError:
            try:
                _get_messages(first_example.inputs)
            except InputFormatError:
                raise InputFormatError(
                    "Example inputs do not match language model input format. "
                    "Expected a dictionary with messages or a single prompt."
                    f" Got: {first_example.inputs}"
                    " Please update your dataset OR provide an input_mapper"
                    " to convert the example.inputs to a compatible format"
                    " for the llm or chat model you wish to evaluate."
                )
def _validate_example_inputs_for_chain(
    first_example: Example,
    chain: Chain,
    input_mapper: Optional[Callable[[Dict], Any]],
) -> None:
    """Validate that the example inputs match the chain input keys."""
    if input_mapper:
        first_inputs = input_mapper(first_example.inputs)
        missing_keys = set(chain.input_keys).difference(first_inputs)
        if not isinstance(first_inputs, dict):
            raise InputFormatError(
                "When using an input_mapper to prepare dataset example"
                " inputs for a chain, the mapped value must be a dictionary."