phonebook = {
    "John" : 938477566,
    "Jack" : 938377264,
    "Jill" : 947662781
}

phonebook["Jake"] = 938273443
del phonebook["Jill"]

if "Jake" in phonebook:
    print("Jake is listed in the phonebook.")

if "Jill" not in phonebook:
    print("Jill is not listed in the phonebook.")