def hash(self) -> str:
        """
        Generate a hash to uniquely identify the media resource.

        The hash is generated based on the available content (data, path, text or url).
        Returns an empty string if no content is available.
        """
        bits: list[str] = []
        if self.text is not None:
            bits.append(self.text)
        if self.data is not None:
            # Hash the binary data if available
            bits.append(str(sha256(self.data).hexdigest()))
        if self.path is not None:
            # Hash the file path if provided
            bits.append(str(sha256(str(self.path).encode("utf-8")).hexdigest()))
        if self.url is not None:
            # Use the URL string as basis for hash
            bits.append(str(sha256(str(self.url).encode("utf-8")).hexdigest()))

        doc_identity = "".join(bits)
        if not doc_identity:
            return ""
        return str(sha256(doc_identity.encode("utf-8", "surrogatepass")).hexdigest())

        Generate a hash to uniquely identify the media resource.

        The hash is generated based on the available content (data, path, text or url).
        Returns an empty string if no content is available.
        
llama-index-core/llama_index/core/schema.py