Fetches nodeHash based on start leaf and height of the node in the tree.

        :return: the nodeHash

def readNodeByTree(self, start, height=None):
        """
        Fetches nodeHash based on start leaf and height of the node in the tree.

        :return: the nodeHash
        """
        pos = self.getNodePosition(start, height)
        return self.readNode(pos)