import M1._+− +− +− +− assert(get_prices(List("GOOG", "AAPL"), 2010 to 2012) ==+− List(List(Some(312.204773), Some(26.782711)), +− List(Some(301.0466), Some(41.244694)), +− List(Some(331.462585), Some(51.464207))))+− +− +−