[sefas24]

Describe your changes

Week04 homework:

• functions_sefa_sagirli.py: custom_power (lambda), custom_equation (annotated, reST docstring, type checks) and fn_w_counter (counts total calls and calls per caller).
• decorators_sefa_sagirli.py: performance decorator that stores counter, total_time and total_mem statistics.

Checklist

• I have read the [CONTRIBUTING]
• I have performed a self-review of my own code
• I have run the code locally and it works as expected
• I have commented my code, particularly in hard-to-understand areas