def _extract_content(self, value, content_keys=["content"]):
        """
        Extracts the 'content' from various data types commonly used by libraries
        like OpenAI, Canopy, LiteLLM, etc. This method navigates nested data
        structures (pydantic models, dictionaries, lists) to retrieve the
        'content' field. If 'content' is not directly available, it attempts to
        extract from known structures like 'choices' in a ChatResponse. This
        standardizes extracting relevant text or data from complex API responses
        or internal data representations.

        Args:
            value: The input data to extract content from. Can be a pydantic
                   model, dictionary, list, or basic data type.

        Returns:
            The extracted content, which may be a single value, a list of values,
            or a nested structure with content extracted from all levels.
        """
        return signature_utils._extract_content(
            value, content_keys=content_keys
        )

        Extracts the 'content' from various data types commonly used by libraries
        like OpenAI, Canopy, LiteLLM, etc. This method navigates nested data
        structures (pydantic models, dictionaries, lists) to retrieve the
        'content' field. If 'content' is not directly available, it attempts to
        extract from known structures like 'choices' in a ChatResponse. This
        standardizes extracting relevant text or data from complex API responses
        or internal data representations.

        Args:
            value: The input data to extract content from. Can be a pydantic
                   model, dictionary, list, or basic data type.

        Returns:
            The extracted content, which may be a single value, a list of values,
            or a nested structure with content extracted from all levels.
        
src/core/trulens/core/app.py