Follow up PR for changes requested in #445

[ramvikrams]

• Closes #xxxx (Replace xxxx with the Github issue number)
• Tests added: Please use assert_type() to assert the type of any return value

Follow up PR for #445

Added the two value_counts method as told, tried to change the tests but I have some questions here:-

1. Sir actually when I write test check(assert_type(c1, pd.Series[int]), pd.Series, pd.Series[int])
   it shows this error Type application has too few types (2 expected) [misc] it only works when we write the test like
   this check(assert_type(c1, pd.Series[int]), pd.Series)
2. and when the above change is made pytest does not work it shows this error type' object is not subscriptable
   and only works when we write the test like check(assert_type(c1, pd.Series), pd.Series) but mypy fails here it says Expression is of type "Series[float]", not "Series[Any]" [assert-type]
3. @Dr-Irv Sir the recent changes you made in test_pandas.py in line 1443 also shows this error Failed: DID NOT WARN. No warnings of type (<class 'FutureWarni... while running poe pytest

[Dr-Irv]

This should be check(assert_type(c1, "pd.Series[int]"), pd.Series, int) and similar for the next one.

[ramvikrams]

done the changes, sir

[Dr-Irv]

Thanks @ramvikrams

[ramvikrams]

Thanks @ramvikrams

Welcome sir