This is a way to build Python 3.7 from source and temporarily install it in Amazon Linux 2 without
overwriting the system Python and without interfering with the Python in amazon-linux-extras.
At the time of this writing, Amazon Linux 2 offers Python 2.7.14 and (through the extras) Python 3.6.2, but Python 3.7.0 was just released.
- Start Amazon Linux 2 and sign in. (I recommend a c5.large instance.)