code: def add_file(self, filename, block_size=4096):
          
          with open(filename, "rb") as f:
              for chunk in iter(lambda: f.read(block_size), b""):
                  self.hash.update(chunk)
docs: 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