Python built-in function id

English documentation:

id(object)

Return the “identity” of an object. This is an integer which is guaranteed to be unique and constant for this object during its lifetime. Two objects with non-overlapping lifetimes may have the sameid() value.

CPython implementation detail: This is the address of the object in memory.

Description:

　　　1. Return the unique identifier of the object, expressed as an integer. This identifier constant is unique during the lifetime of the program.

>>> a = 1
>>> id(a)
>>> id(1.0)
>>> a = 'some text'
>>> id(a)