Is dockerfile of jupyter-notebook in example newest?

Hello,

I am trying to build jupyter-notebook image based on Dockerfile.cpu in example directory:

container-engine-accelerators/example/tensorflow-notebook-image/Dockerfile.cpu

FROM ubuntu:latest

but got following error:

Package libav-tools is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
  ffmpeg

E: Package 'libav-tools' has no installation candidate
The command '/bin/sh -c apt-get update && apt-get install -yq --no-install-recommends     apt-transport-https     build-essential     bzip2     ca-certificates     curl     emacs     fonts-liberation     g++     git     inkscape     jed     libav-tools     libcupti-dev     libsm6     libxext-dev     libxrender1     lmodern     locales     lsb-release     openssh-client     pandoc     pkg-config     python     python-dev     sudo     unzip     vim     wget     zip     zlib1g-dev     && apt-get clean &&     rm -rf /var/lib/apt/lists/*' returned a non-zero code: 100

After change libav-tools to ffmpeg will fix this error.So is the dockerfile newest or not?