new_employee_email = "jswift@email.com"
new_employee_details = {
    "first_name": "Jane", 
    "last_name": "Swift", 
    "address": {
        "city": "Boston", 
        "street": "10th Street", 
        "house_number": 10
    }
}

# dictionary[key] = value
employees[new_employee_email] = new_employee_details

pp.pprint(employees)