OOP Python, adding to the all instance objects, but I only want to add to one

Question

Here I am having trouble adding a trick to only one dog. Every time I try to add to one dog, it will add to all of them instead. (The test cases expected results are on the bottom) Thanks!

class Dog:
    def __init__(self, name, tricks=set()):
        self.name = name
        self.tricks = tricks
    def teach(self, trick):
        self.tricks.add(trick)
        
# Change the broken code above so that the following lines work:
# 
# buddy = Dog('Buddy')
# pascal = Dog('Pascal')
# kimber = Dog('Kimber', tricks={'lie down', 'shake'})
# buddy.teach('sit')
# pascal.teach('fetch')
# buddy.teach('roll over')
# kimber.teach('fetch')
# print(buddy.tricks)  # {'sit', 'roll over'}
# print(pascal.tricks)  # {'fetch'}
# print(kimber.tricks)  # {'lie down', 'shake', 'fetch'}