At , the branch value is the complete elliptic integral of the first kind
A contour that goes once around and then to applies the reflection about , giving
Similarly, the branch value at is , so a loop around acts as . A contour that loops first around and then around therefore gives
Finally approach the interval through the upper half-plane. There
so the branch value at is
It follows that a loop around acts as
A contour that loops first around and then around consequently gives
Here is the complementary complete elliptic integral of the first kind. These contours exhibit all three requested values.