diff --git a/tree.h b/tree.h
index 78523d7..9158011 100644
--- a/tree.h
+++ b/tree.h
@@ -24,16 +24,25 @@ enum expr_type {
  */
 struct expr_node {
     enum expr_type type;
+
+    /* hodnoty dle typu uzlu */
     union expr_vals {
+        /* operandy u binární operace */
         struct expr_binop_vals {
             struct expr_node *left;
             struct expr_node *right;
         } binop;
+
+        /* argumenty funkce */
         struct expr_fn_vals {
             size_t fn_idx;
             struct expr_node *args[MAX_MATH_FUNCTION_ARGS];
         } fn;
+
+        /* unární operand */
         struct expr_node *unop;
+
+        /* hodnota konstanty */
         double num;
     } vals;
 };