Flask is one of the popular web frameworks in python. To check the version of the flask package installed in an environment, you can use one of the following methods.
Using python interpreter
import flask
flask.__version__
Using command line
flask --version
Using pip (if flask is installed using pip or easy_install command)
In Linux OS
pip freeze | grep flask
In Windows OS
pip freeze | findstr "Flask"
I hope this tip is useful. Feel free to comment in case of any issues.