Calculate Sortino Ratio - Quant Researcher Interview Question

Problem Description

The Sortino Ratio improves upon the Sharpe Ratio by penalizing only downside volatility, offering a more accurate risk-adjusted performance measure for return distributions that are not normally distributed. By focusing exclusively on returns falling below a specific target, it helps investors distinguish between harmful volatility and general price fluctuations. Task Implement a function solution(returns, target_return) that calculates the Sortino Ratio given a list of historical returns and a