Write a function named "read_prices" that takes one parameter that is a list of ticker symbols that your company owns in their portfolio. you are to read a csv file for each of these tickers which contains the price of each stock throughout the year and return these prices in a single dictionary. the returned dictionary will contain ticker symbols as keys and dictionaries as values where the inner dictionaries will have dates as keys (as strings in the format "-mm-dd") and prices as values as floats. all said this dictionary will contain the price for any stock on any date over the past year