How does a function know the docstring of its code object?

[Arnaud Delobelle]

Hi all,

You can do:

def foo():
"foodoc"
pass

function = type(lambda:0)
foo2 = function(foo.__code__, globals())
assert foo2.__doc__ == "foodoc"

I am wondering how the function constructor knows that foo.__code__
has a docstring. I can see that

foo.__code__.co_consts == ('foodoc',)

But I can't find where in foo.__code__ is stored the information that
the first constant in foo.__code__ is actually a docstring.