contact all_contacts [ send_mail("hellotest -mail here"sending mail to jsmith@example net the contact initializer is still adding the new contact to the all_contacts listand the mixin is able to send mail to self email so we know everything is working this wasn' so hardand you're probably wondering what the dire warnings about multiple inheritance are we'll get into the complexities in minutebut let' consider some other options we hadrather than using mixin herewe could have used single inheritance and added the send_mail function to the subclass the disadvantage here is that the -mail functionality then has to be duplicated for any other classes that need -mail we can create standalone python function for sending an -mailand just call that function with the correct -mail address supplied as parameter when the -mail needs to be sent we could have explored few ways of using composition instead of inheritance for exampleemailablecontact could have mailsender object instead of inheriting from it we could monkey-patch (we'll briefly cover monkey-patching in python object-oriented shortcutsthe contact class to have send_mail method after the class has been created this is done by defining function that accepts the self argumentand setting it as an attribute on an existing class multiple inheritance works all right when mixing methods from different classesbut it gets very messy when we have to call methods on the superclass there are multiple superclasses how do we know which one to callhow do we know what order to call them inlet' explore these questions by adding home address to our friend class there are few approaches we might take an address is collection of strings representing the streetcitycountryand other related details of the contact we could pass each of these strings as parameter into the friend class' __init__ method we could also store these strings in tuple or dictionary and pass them into __init__ as single argument this is probably the best course of action if there are no methods that need to be added to the address