Cairo 0.10.0 Error: Cannot unpack return value error

With the update to Cairo 0.10.0, is_le now returns a felt not a tuple as it did before.

Previously the signature looked like:

func is_le{range_check_ptr}(a, b) -> (res: felt):

Now it looks like:

func is_le{range_check_ptr}(a, b) -> felt {

with this in mind make sure you do not unpack the result of function that return a felt. You should have your code like:

let is_negative : felt = is_le(x, -1);

ㅤ This answer was originally posted on Triality