How should I create python module to calculate frequency.

MITRESH POONIA Could you please describe in detail what you intend to do? Your question is ambiguously to me. Frequency can be derived from the number of cars passing a street crossing in a specified time interval, or frequency can refer to extracting frequencies out of a digitized sound signal by means of fourier analysis.

It could also refer to how often a letter appears in a sentence or statement. It could be as simple as implementing a count function

The question is to calculate how many times a letter is appearing in the function

There are many ways to achieve this, I have attached an example below for you. Copy it for yourself as I normally delete after a couple of days https://code.sololearn.com/cqR8yt4u8Mmm/?ref=app