It happens that different bioinformatic tools that we want to install requires specific python library versions. What makes it worse is  that sometimes the python libraries that they required could be incompatible with each other, leaving our local python environment as a messy place to manage. Anaconda is a great tool to manage local python environment and libraries. With Anaconda, we can easily create isolated virtual environment for a specific python version:

# download the latest Anaconda distribution for Linux
$ wget https://repo.continuum.io/archive/Anaconda3-5.0.1-Linux-x86_64.sh
# use conda to create a python 3.5 environment named "py35"
$ conda create -n py35 python=3.5 anaconda
# activate the py35 environment
$ source activate py35
# to verify the current active python version
$ python --version

Reference

https://conda.io/docs/user-guide/tasks/manage-python.html