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# Remember a and b are _names_ for the list. They both have the _same_ value.
a.append(35) # Modify the value.
print(a)
print(b)
# We mutated (changed) the value, its names still point to the _same thing_, so it doesn't matter which name you use.
a= []
b= []
a.append(35)
print(a)
print(b)
# Here they are different lists, because [] creates a new list every time. You can check whether two things are the _same_ one by usingt the `id()` function:
print(id(a))
print(id(b)) # Different from id(a)
# -- immutable --
# Some values can't be changed because they don't have methods that modify the value itself.
# In case of the list, `.append()` mutates the list.
# For example integers don't have any such methods, so they are called _immutable_.
a=8597
b=8597
print(id(a))
print(id(b)) # Same one
a=8598
print(id(a))
print(
id(b)
) # Different, because we didn't change 8597. We just used the name 'a' for a different value. 'b' still is a name for 8597.
# Most things are mutable in Python. If you want to keep one of your classes immutable, don't add any methods that change the objects' properties.
# Tuples and strings are the only fundamental collection in Python which is immutable.
# Lists, sets, dictionaries are all mutable.
# Integers, floats, and booleans are all immutable.
# -- += and similar --
# A lot of beginners think this:
a="hello"
b=a
print(id(a))
print(id(b))
a+="world"
# Would cause 'b' to change
# But it doesn't, because strings are immutable. When you do str + str, a _new_ string is created.
# This means that a becomes a new string containing "helloworld", but b still is a name for "hello".
