My solution for the extra credit assignment

import re

with open('names.txt') as f:
    data = f.read()

regex = re.compile(r'''
    ^(?P<last_name>[-\w ]+)?,\s # Last Name
    (?P<first_name>[-\w ]+)\t  # First Name
    (?P<email>[-\w\d.+]+@[-\w\d.]+)\t  # Email
    (?P<phone>\(?\d{3}\)?-?\s?\d{3}-\d{4})?\t  # Phone
    (?P<job>[\w\s]+,\s[\w\s.]+)\t?  # Job and company
    (?P<twitter>@[\w\d]+)?$  # Twitter
''', re.M|re.X)

class Person:
    def __init__(self, *args, **kwargs):
        for k, v in kwargs.items():
            setattr(self, k, v)

    def __repr__(self):
        return f"{self.first_name} {self.last_name} <{self.email}>"     

class AddressBook:
    def __init__(self):
        self.people = []

    def add(self, other):
        self.people.append(other)

    def __repr__(self):
        return self.people

    def __str__(self):
        return str(self.people)

    def find_where_equals(self, parameter_name, value):
        "Return list of people"
        return [person for person in self.people if hasattr(person, parameter_name) \
                                                 and str(value) == str(getattr(person, parameter_name))]     

    def find_where_contains(self, parameter_name, value):
        "Return list of people"
        return [person for person in self.people if hasattr(person, parameter_name) \
                                                 and value in str(getattr(person, parameter_name))]

address_book = AddressBook()

# Populating address book with data from file
for entry in regex.finditer(data):
    person = Person(**entry.groupdict())
    address_book.add(person)

# Some examples of usage of the address book
print(address_book.find_where_equals('first_name', 'Kenneth'))
print(address_book.find_where_contains('phone', '5'))

for person in address_book.find_where_contains('phone', '5'):
    print(person.phone)