直接安裝 apt-get install python3.6 ，失敗，出現
E: Unable to locate package python3.6
E: Couldn't find any package by glob 'python3.6'
E: Couldn't find any package by regex 'python3.6
這是因爲Ubuntu無法找到add-apt-repository問題的解決方法
解決方法是：
apt-get install python-software-properties
apt-get install software-properties-common
add-apt-repository ppa:jonathonf/python-3.6
然後執行
apt-get update
再執行
apt-get install python3.6