So while the behaviour is surprising, the language is behaving as designed:  the target of `del` is considered to be a local variable for the entire function definition.  (In much the same way, the targets of simple assignments are considered local, so if you'd assigned to "Foo" in the "if False:" block, you'd see the same error.)

The behaviour is documented here: https://docs.python.org/3.4/reference/executionmodel.html#naming-and-binding

Note particularly these bits:

"If a name is bound in a block, it is a local variable of that block, [...]"

"A target occurring in a del statement is also considered bound for this purpose [...]"

See also this FAQ: https://docs.python.org/3/faq/programming.html#id8

I wonder whether it's worth updating the FAQ to mention that `del` is considered to bind names in this way.