Create a public class BinaryTreeCounter that provides a single class method named countChildSumToNegative that accepts a single BinaryTree<Integer> and counts the number of nodes in the tree where the values of the node's children sum to a negative number. You should not count nodes that don't have at least one child, but some nodes may only have one child. Keep in mind that not every node has a right or left child, so you'll need to check for null carefully. However, you can assume that all of the values in the tree are non-null Integers.

For reference, cs125.trees.BinaryTree has the following public properties: