我正在尝试在 Ubuntu 20.04.1 LTS 上安装 Torch http://torch.ch/docs/getting-started.html
当我运行时
cd ~/torch; bash install-deps;
它会产生此错误：
Package ipython 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
E: Package 'ipython' has no installation candidate
如何安装 ipython？