Python

def stocks_value(portfolio): return None 

if __name__ == '__main__': 

 portfolio1 = [('CAT', 25, 43.50, 67.75), ('MSFT', 100, 87.65, 82.50), ('IBM', 35, 90.15, 92.97), ('APPL', 200, 175.00, 255.65)] portfolio2 = [('GOOG', 250, 325.86, 278.90), ('ABC', 115, 25.60, 29.85)] print('Testing stocks_value() for portfolio #1: ' + str(stocks_value(portfolio1))) print('Testing stocks_value() for portfolio #2: ' + str(stocks_value(portfolio2))) 

In addition to lists and dictionaries Python offers another type of collection called a tuple (pronounced "tupple" or "toople"). A tuple is a container for a fixed, immutable collection of values. This means that elements inside of a tuple cannot be changed or deleted. It also means that new items cannot be added to an existing tuple. In Python, a tuple is de noted using parentheses. Here are some examples of tuples: sizes small', 'medium', large', 'extra large ages (22, 29, 25, 30, 19, 24) info ('Jane Smith' 21, 3. 91) Note that we can mix data types within a single tuple. To access the elements of a tuple we can use bracket notation. For instance, the following code would print the string large on the screen: print (sizes [2]) Imagine we had a portfolio of stocks we purchased and then later sold. Here is an example: Symbol of Shares Purchase Price Selling Price 67.75 CAT 25 43.50 MSFT 100 87.65 82.50 IBM 35 90.15 92.97 APPL 200 255.65 175.00 We could represent these four stock transactions using a list of tuples: portfolio CAT' 25, 43.50, 67.75) ('MSFT', 100, 87.65, 82.50)