On My Ubuntu, apt-get install python3 installs python3.2.
Even though I installed python3.5 with apt-get install python3.5, It just install another python3.5 not to upgrading python3. (It means there are two python version3 python3 and python3.5)
At the first I remove python3(python3.2) with apt-get --purge autoremove python3 to avoid crash between two python version3.
However, when I try to install packages having dependency for python3, Ubuntu reinstall python3.2 even if I have python3.5 and the package refer to python3.2.(for example python3-lxml)
How can I solve it ?