First, what is variable
Variables can be understood from the literal meaning: is the amount of change. I know the computer by recording our state. This is the concept of quantity.
Capacity: recording status in the real world, so that the computer can like people to identify things in the world.
Change: the state of the real world will change happen.
Second, the definition of variables (compositional variables)
Variable names assign symbolic variable values
python Example: age = 18
Third, memory management
Among the variables stored in memory, if the variable reference count value is not binding, it will be cleaned up to free up memory.
[-5,256] is a small integer pool will not be cleaned up.
Fourth, fancy assignment
Chain assignment
Example: A = B = C = D = 10
Cross assignment
例：x,y = y,z