How to get python object or variable unique id value

If you have a python object or variable, you can get its unique id by id() function, this value can be regarded as its memory address.

>>> x=7
>>> id(x)
38166456L
>>> y=x
>>> id(y)
38166456L

You must notice, the id of x and y is the same. the value of them may be different in different system.