Being man-made doesn't make identity any less real. As a particular example, there's a big semantic difference in Python between `foo is bar` and `foo == bar`, with the former based on the interpreter's memory allocation and the latter allowing a custom class to decide its own answer. And the former is actually really implementation-dependent, with the following being True in cpython for any integer in the range [-5, 256]:

`a = 257; b = a*1; a is b`