PYTHON : Pandas groupby.size vs series.value_counts vs collections.Counter with multiple series

To Access My Live Chat Page,
On Google, Search for "hows tech developer connect"

As promised, I'm going to share a hidden feature with you.
This is a YouTube's feature which works on Desktop.
First, Ensure that the video is playing before proceeding.
Then, type the letters 'awesome' on the keyboard.
The progress bar on YouTube will be altered to a flashing rainbow.

An introduction to myself in a few words,
Hello everyone, I'm Delphi.
Let me aid you in resolving any queries you may have.
Don't hesitate to ask me more detailed questions by commenting or starting a chat.
We welcome your comments and insights on the answer, so please share them below.
A 'heart' from me is a way of showing appreciation for your answer.