In your example, 1 < "a" because "i" for int comes alphabetically before "s" for string.
From the docs:
Objects of different types, except different numeric types and
different string types, never compare equal; such objects are ordered
consistently but arbitrarily (so that sorting a heterogeneous array
yields a consistent result).
I believe this was one of the things changed in python 3 (you would get a TypeError here).
As for how it is done in CPython, objects of different types except numbers are ordered by their type names; objects of the same types that don’t support proper comparison are ordered by their address. Note that this is part of the implementation, not a part of the language.
