Start implementing and testing the Contacts class. The Contacts should extend the built$-$in list class. Otherwise, you would have to implement all the methods already provided by list.

The Contacts class should NOT have an initializer. That is$,$ it uses its parent initializer.

A method you have to add, however, is the count$\_$duplicates method which takes only self as an argument and returns an integer. This will be highly dependent on your correct implementation of Person.$\_\_$eq$\_\_().$ The count duplicate $($as given by the name$)$ should count how many of its elements are the same. For example, if we have the list $[$a$,$ b$,$ a$,$ a$],$ the count of duplicates is $1($even if the value a was observed three times, we say that a itself has a duplicate thus the count is $1).$ In your case, you will be considering a person's object instead of the letters a or b$.$

count duplicate should work in this test case

def setUp$($self$)->$ None:

$"""$The setUp method is a built$-$in method on unittest that

is called freshly each time you call any of the test methods below.

$"""$

self.a$1=$ person.Person$("$Ahmad$",\{\text{'}$primary$\text{'}$: $123456789,$ 'mobile': $223344556\},$ "ahmad@institution.edu"$)$

self.a$2=$ person.Person$("$Ahmad$",\{\text{'}$primary$\text{'}$: $123456789,$ 'mobile': $223344556\},$ "ahmad@institution.edu"$)$

self.khaled $=$ person.Person$("$Khalid$",\{\text{'}$primary$\text{'}$: $91919191,$ 'mobile': $102030405\},$ "khalid@institution.edu"$)$

self.a$\_$different$\_$khaled $=$ person.Person$("$Khaled$",\{\text{'}$primary$\text{'}$: $91919191,$ 'mobile': $102030405\},$

"khalid@institution.edu"$)$

def test$\_$duplicates$($self$)$:

$"""$Test if two elements in contacts are duplicates. This also depends on

the equality check for Person. However, it also depends on how you define

duplicates in Contact as the method is not inherited from list.

$"""$

c$1=$ contacts.Contacts$()$

# only one item in the list, there is no way we have duplicates

c$1.$append$($self$.$a$1)$

self.assertEqual$(0,$ c$1.$count$\_$duplicates$())$

# the same person added, we now should have one duplicate

c$1.$append$($self$.$a$1)$

self.assertEqual$(1,$ c$1.$count$\_$duplicates$())$

# a different instance is added for the same person's information, the duplicate count should stay the same

c$1.$append$($self$.$a$2)$

self.assertEqual$(1,$ c$1.$count$\_$duplicates$())$

# we added a person that we know was never in the list, duplicate count should stay the same

c$1.$append$($self$.$khaled$)$

self.assertEqual$(1,$ c$1.$count$\_$duplicates$())$

# we added a person with very close information as with the one above but not really the same.

c$1.$append$($self$.$a$\_$different$\_$khaled$)$

self.assertEqual$(1,$ c$1.$count$\_$duplicates$())$

# we added the original instance for Khaled, the count should go up by one.

c$1.$append$($self$.$khaled$)$

self.assertEqual$(2,$ c$1.$count$\_$duplicates$())$