langchain/chat_models/anthropic.py/ChatAnthropic/_convert_messages_to_text
class ChatAnthropic:    def _convert_messages_to_text(self, messages: List[BaseMessage]) -> str:
        """Format a list of strings into a single string with necessary newlines.

        Args:
            messages (List[BaseMessage]): List of BaseMessage to combine.

        Returns:
            str: Combined string with necessary newlines.
        """
        return "".join(
            self._convert_one_message_to_text(message) for message in messages
        )