Differences between = and <- in Python

Think of Python's variable as basically storing addresses

>>> a = [1,2,3]
>>> b = a

If so, a stores an address value that can refer to [1,2,3] and b stores the same address value that is stored in a.

Therefore, if you work with a.append(4), b stores the same address value as a, so if you output a and b, you will get [1, 2, 3, 4].

>>> a = [1, 2, 3]
>>> b = a
>>> a = [1, 2, 3, 4]

If you do it as above, b stores the address value that a previously pointed to, but a stores the new address value, so the two exist separately.

If you want to distinguish between a and b in a universal situation including a list, you can do the following.

import copy
a = [1, 2, 3]
b = copy.deepcopy(a)

>>> a
[1, 2, 3]
>>> b
[1, 2, 3]
>>> a.append(4)
>>> a
[1, 2, 3, 4]
>>> b
[1, 2, 3]

Watch this.

Summary: Python does not have a <- operator, but you probably misread the < and the negative sign -

If you declare A = B and touch A afterwards, does B change as well?

Yes.

Many use methods such as A = B[:] to create and assign replicas using full slicing.