question: public S2Cap complement ( ) { double cHeight = isFull ( ) ? - 1 : 2 - Math . max ( height , 0.0 ) ; return S2Cap . fromAxisHeight ( S2Point . neg ( axis ) , cHeight ) ; }
target:  Return the complement of the interior of the cap. A cap and its complement have the same boundary but do not share any interior points. The complement operator is not a bijection, since the complement of a singleton cap (containing a single point) is the same as the complement of an empty cap.