úÎ F ù      8dimension returns the number of coordinates of a point. coord gets the k' th coordinate, starting from 0. 7dist2 returns the squared distance between two points. ?compareDistance p a b compares the distances of a and b to p. Hinvariant tells whether the KD tree property holds for a given tree and  all its subtrees. L Specifically, it tests that all points in the left subtree lie to the left M of the plane, p is on the plane, and all points in the right subtree lie to  the right.               KdTree-0.1Data.Trees.KdTreeKdTreeKdEmptyKdNodekdLeftkdPointkdRightkdAxisPoint3dp3xp3yp3zPoint dimensioncoorddist2compareDistancefromListfromListWithDepth axisFromDepthtoListsubtreesnearestNeighbor invariant invariant'