radix.go
func NewFromMap(m map[string]interface{}) *Tree {
	t := &Tree{root: &node{}}
	for k, v := range m {
		t.Insert(k, v)
	}
	return t
}
func NewFromMap(m map[string]interface{}) *Tree {
	t := &Tree{root: &node{}}
	for k, v := range m {
		t.Insert(k, v)
	}
	return t
}
// NewFromMap returns a new tree containing the keys
// from an existing map