1 

     2 // get_prices(List("GOOG", "AAPL"), 2010 to 2012)

     3 val urban_prices = List(List(Some(311.349976), Some(20.544939)), 

     4                         List(Some(300.222351), Some(31.638695)), 

     5                         List(Some(330.555054), Some(39.478039)))

     6 

     7 

     8 assert(get_deltas(urban_prices) == List(List(Some(-0.03573992567129673), Some(0.539975124774038)), 

     9                                         List(Some(0.10103412653643493), Some(0.24777709700099845))))

    10 

    11 

    12 //get_prices(List("BIDU"), 2004 to 2008)

    13 val urban_prices2 = List(List(None), List(None), 

    14                          List(Some(6.35)), List(Some(12.241)), 

    15                          List(Some(38.188)))

    16 

    17 

    18 assert(get_deltas(urban_prices2) == List(List(None), List(None), 

    19                                         List(Some(0.9277165354330709)), 

    20                                         List(Some(2.119679764725104))))