refactor: make pull request items requirements

TheAlgorithms · cclauss · Oct 26, 2021 · Oct 24, 2021 · Oct 24, 2021 · Oct 24, 2021
commit ff0cde76e69efb1ee36b258d633009dce1fceeac
diff --git a/financials/ABOUT.md b/financials/ABOUT.md
@@ -1,12 +1,5 @@
-## About math calculations
-
 ### Interest
 
 * Compound Interest: "Compound interest is calculated by multiplying the initial principal amount by one plus the annual interest rate raised to the number of compound periods minus one." [Compound Interest](https://www.investopedia.com/) 
 * Simple Interest: "Simple interest paid or received over a certain period is a fixed percentage of the principal amount that was borrowed or lent. " [Simple Interest](https://www.investopedia.com/)
 * 
-
-### Average
-
-//todo
-
diff --git a/financials/__init__.py b/financials/__init__.py
diff --git a/financials/average.py b/financials/average.py
diff --git a/financials/interest.py b/financials/interest.py
@@ -1,8 +1,23 @@
-def simple_interest(principle, daily_interest_rate, number_of_days_between_payment):
+from __future__ import annotations
+
+def simple_interest(principle, daily_interest_rate, number_of_days_between_payment) -> float:
+    """
+    >>> simple_interest(18000,0.06,3)
+    3240.0
+    """
     result = principle * daily_interest_rate * number_of_days_between_payment
     return result
 
-def compound_interest(principle, nominal_annual_interest_rate_percentage , number_of_compounding_periods):
+def compound_interest(principle, nominal_annual_interest_rate_percentage , number_of_compounding_periods)-> float:
+    """
+    >>> compound_interest(10000,0.05,3)
+    1576.2500000000014
+    """
     result = principle * ((1 + nominal_annual_interest_rate_percentage) ** number_of_compounding_periods - 1)
     return result
 
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()