lists can be modified without replacing the original object : id « Buildin Function « Python Tutorial

1. Python Tutorial
2. Buildin Function
3. id

aList = ['A', 83, 85, 'B']
print aList
print aList[2]
print id(aList)
aList[2] = aList[2] + 1
aList[3] = 'C'
print aList
print id(aList)
print aList.append('D')
print aList.append(aList[2] + 1)
print aList
print id(aList)