func (t *Tree) DeletePrefix(s string) int {
	return t.deletePrefix(nil, t.root, s)
}
func (t *Tree) DeletePrefix(s string) int {
	return t.deletePrefix(nil, t.root, s)
}
func ( t * Tree ) DeletePrefix ( s string ) int { return t . deletePrefix ( nil , t . root , s ) }
// DeletePrefix is used to delete the subtree under a prefix
// Returns how many nodes were deleted
// Use this to delete large subtrees efficiently
DeletePrefix is used to delete the subtree under a prefix Returns how many nodes were deleted Use this to delete large subtrees efficiently