in progress commit

- fill out eval skele
- documentation comments in var tabel

src/vars.rs

@@ -26,6 +26,7 @@ use crate::segment::{Ctr};
  */
 pub type VTable = HashMap<String, Rc<Ctr>>;
 
+// WARNING: make sure var_tree is properly evaluated before storing
 pub fn define(
     vt: Rc<RefCell<VTable>>,
     identifier: String,