How to detect Python version at runtime   

Most people knowns to detect python version by:

python -V

From the command line. But if you want to detect the python version from the code itself then you can use the sys.version:

Detect Python runtime with sys.version

import sys
print("Current Python version: ", sys.version)

result(this result is for portable WinPython on Windows):

Current Python version: 3.5.3 (v3.5.3:1880cb95a742, Jan 16 2017, 16:02:32) [MSC v.1900 64 bit (AMD64)]

You can check more details with:

import sys
print("Python version: ", sys.version_info)

result:

Current Python version: sys.version_info(major=3, minor=5, micro=3, releaselevel='final', serial=0)

Detect Python runtime with platform

There is one more way by using platform:

import platform
print(platform.python_version())

result:

3.5.3

The other way by using platform is:

import platform
print(platform.sys.version)

result:

3.5.3 (v3.5.3:1880cb95a742, Jan 16 2017, 16:02:32) [MSC v.1900 64 bit (AMD64)]

Which way you are going to use depends on your needs - code compability and information required for the version.

Warning for older python versions

Warning in case of usage of Python 2 and older:

import sys
if sys.version_info[0] < 3:
    raise Exception("Please upgrade to Python 3")

result:

Please upgrade to Python 3

Detect specific Python version and alert in case of other version:

import sys

if sys.version_info[0] != 3 or sys.version_info[0] != 7:
    print("Please upgrade to the latest version 3.7.\n")
    sys.exit(1)

print("Current Python version: ", sys.version)

result:

Please upgrade to the latest version 3.7.