Tests in the 04-phonebook refer to the functions that are neither defined by default nor asked to be implemented

[Sampo-K]

Tests refer to the phonebook._to_string() and phonebook._read() that are not included in the specification of the phonebook.py file. I implemented these myself by checking what the test code does but should the assignment be done in this way? I think this is not clearly stated in the assignment documentation.

Another slightly confusing thing in the assignment documentation was that the regexp part talks about regexp that requires the phone number to start with "+" but the actual assignment accepts both numbers with and without "+" as it uses a bit different regexp.