00A.
Before applying a rabbitearfold, you need to look for a triangular region.
In a typical squarepaper (shown on the left), you can have either an upper triangular region or a lower triangular region.
If we have a vertical dotted line instead, then we will have a left triangular region and a right triangular region instead.
In this example, we will choose the upper triangular region but you can choose any region.
