def add_file(self, filename, block_size=4096):
        """
        Add an entire file to this hash.
        :param filename: str filename of the file to hash
        :param block_size: int size of chunks when reading the file
        """
        with open(filename, "rb") as f:
            for chunk in iter(lambda: f.read(block_size), b""):
                self.hash.update(chunk)