diff --git a/The-Nook-GamesTM/Fundamentals/basic_tree.c b/The-Nook-GamesTM/Fundamentals/basic_tree.c
index 700cebd..0b6da9c 100644
--- a/The-Nook-GamesTM/Fundamentals/basic_tree.c
+++ b/The-Nook-GamesTM/Fundamentals/basic_tree.c
@@ -4,7 +4,7 @@
 #include <sys/types.h>
 #include <time.h>
 // FCTs perso
-
+/*
 struct queue *enqueue(struct queue *queue, struct node *node){
 
     //if (!queue || !node) return NULL;
@@ -53,7 +53,7 @@ void queue_destroy(struct queue *queue){
     free(tmp);
     }
 }
-
+*/
 void delete_tree(struct node *root){
     
     if(!root) return;
diff --git a/The-Nook-GamesTM/Proficiencies/utils.h b/The-Nook-GamesTM/Proficiencies/utils.h
new file mode 100644
index 0000000..9638803
--- /dev/null
+++ b/The-Nook-GamesTM/Proficiencies/utils.h
@@ -0,0 +1,20 @@
+#ifndef UTILS_H
+#define UTILS_H
+
+union element_type
+{
+    int operand;
+    char operator;
+};
+
+enum element_tag {
+    TOKEN_OPERAND,
+    TOKEN_OPERATOR
+};
+
+struct expression_element {
+    enum element_tag tag;
+    union element_type data;
+};
+
+#endif /* ! UTILS_H */
\ No newline at end of file