Add GroupBy function and example run

[pearl2201]

Checklist for PR

[x] Link to corresponding Issue. 8 [x] Tests covering all the code branches. [x] Validations for all the argument's type. This includes the functions passed as arguments. [x] A Comment on how the function works and what are the different validations in the function. [x] An ExampleTest of the function. [x] README.md should be updated about the function.

[pearl2201]

I will add test and readme later.

[aswinkarthik]

Could you resolve the conflicts and update the PR?

[pearl2201]

Could you resolve the conflicts and update the PR?

i had merged