Best Stock
You are given the current stock prices. You have to find out which stocks cost more.
Input: The dictionary where the market identifier code is a key and the value is a stock price.
Output: The market identifier code (ticker symbol) as a string.
Example:
bestStock({'ATX': 390.2,
'CAC': 10.0,
'WIG': 1.2}) == 'ATX'
bestStock({'ATX': 1.01,
'CAC': 91.1,
'TASI': 120.9}) == 'TASI'
Preconditions: All the prices are unique.
