dataset is called birdsongs.data

We can create density plots that compare frequencies across both the identity and treatment columns of our full dataset. Make two density plots. In the first, plot all birds in urban locations, comparing nestling versus tutor individuals' song frequencies. In the second, plot all birds in non-urban locations, again comparing nestling versus tutor individuals' song frequencies. Make sure you can see both density distributions and that your axes and legend are appropriately labeled. Add titles to differentiate the two graphs