PYTHON why extend() change my original variable?

Question

(This question already has answers here): question from:https://stackoverflow.com/questions/66057418/python-why-extend-change-my-original-variable

Answer 1

Because both variables a and b reference the same object.

a = ["A","E"]
b = a

print(id(a))
print(id(b))
print(a is b)

output:

140387638915552
140387638915552
True