Add python3.7 as alternate python along with default on Ubuntu

My default python is 2.7 and I want python 3.7 along with it:

1. Go to opt directory $ cd /opt
2. Create a directory $ mkdir python3
3. Download Python 3.7 $ wget https://www.python.org/ftp/python/3.7.4/Python-3.7.4.tgz
4. Extract the python 3.7 tar file $ tar xzf Python-3.7.4.tgz
5. To compile the source go to $ cd Python-3.7.4
6. To get release build with all stable optimizations active (PGO, etc), execute $ sudo ./configure --enable-optimizations Inside Python-3.7.4 directory
7. To prevent replacing of default python binary file /usr/bin/python, use $ sudo make altinstall
8. To confirm the installation use $ python3.7 –version and which python3.7