"""The variable name to format the initial response in when refining."""
    document_prompt: BasePromptTemplate = Field(
        default_factory=_get_default_document_prompt
    )
    """Prompt to use to format each document, gets passed to `format_document`."""
    return_intermediate_steps: bool = False
    """Return the results of the refine steps in the output."""
    @property
    def output_keys(self) -> List[str]:
        """Expect input key.
        :meta private:
        """
        _output_keys = super().output_keys
        if self.return_intermediate_steps:
            _output_keys = _output_keys + ["intermediate_steps"]
        return _output_keys
    class Config:
        """Configuration for this pydantic object."""
        extra = Extra.forbid
        arbitrary_types_allowed = True
    @root_validator(pre=True)
    def get_return_intermediate_steps(cls, values: Dict) -> Dict:
        """For backwards compatibility."""
        if "return_refine_steps" in values:
            values["return_intermediate_steps"] = values["return_refine_steps"]
            del values["return_refine_steps"]
        return values
    @root_validator(pre=True)
    def get_default_document_variable_name(cls, values: Dict) -> Dict:
        """Get default document variable name, if not provided."""
        if "document_variable_name" not in values:
            llm_chain_variables = values["initial_llm_chain"].prompt.input_variables
            if len(llm_chain_variables) == 1:
                values["document_variable_name"] = llm_chain_variables[0]
            else:
                raise ValueError(
                    "document_variable_name must be provided if there are "
                    "multiple llm_chain input_variables"
                )
        else: