PT1_week07

@apietak @gfederic @jbachmann @lbrodbeck @mkryukov Hi!

1. Unfortunately I could not manage to finish the Penna exercise, I tried testing with one simulation but the plot shows that the population remains constant at 0. Moreover I tried to implement the remove_dead() function with the same death_predicate() which is shown in the slides but I found that with the same syntax it did not works and used a lambda function.
2. In the first exercise I found pretty challenging to make my iterator a checked one and neither online nor in the lecture slides there was much information available.

Please be picky with your corrections, thanks!