The Python interpreter compiles programs into bytecode first, and the bytecode includes instructions that load a constant from the constant pool. As an example,

    >>> def f():
    ...     x = 2222; y=2222
    ...     return x is y
    ...
    >>> f()
    True
    >>> f.func_code.co_consts
    (None, 2222)

This last line is showing the constant pool, which is just a standard Python tuple.

I believe the REPL compiles each input in a new toplevel module context, so each input gets its own constant pool.

Functions get their own constant pools, which explains the following behavior:

    >>> if True:
    ...     def f():return 2222
    ...     def g():return 2222
    ...
    >>> f() is g()
    False