def _is_text_field(self, value: Any) -> bool:
        """
        Check if value is a string and keyword filtering needs to be performed.

        Not applied to datetime strings.
        """
        if isinstance(value, str):
            try:
                datetime.fromisoformat(value)
                return False
            except ValueError as e:
                return True
        else:
            return False

        Check if value is a string and keyword filtering needs to be performed.

        Not applied to datetime strings.
        
llama-index-integrations/vector_stores/llama-index-vector-stores-opensearch/llama_index/vector_stores/opensearch/base.py