rearrange builtins

object/null.go

@@ -0,0 +1,17 @@
+package object
+
+type Null struct{}
+
+func (n *Null) Type() ObjectType {
+	return NULL_OBJ
+}
+func (n *Null) Inspect() string {
+	return "null"
+}
+func (n *Null) String() string {
+	return n.Inspect()
+}
+func (n *Null) Equal(other Object) bool {
+	_, ok := other.(*Null)
+	return ok
+}