diff --git a/lukovnikovde/docs/data/DataStructure.py b/lukovnikovde/docs/data/DataStructure.py
index e69de29..dae6e2c 100644
--- a/lukovnikovde/docs/data/DataStructure.py
+++ b/lukovnikovde/docs/data/DataStructure.py
@@ -0,0 +1,33 @@
+import random as rnd
+#############################################################################################
+head = None
+
+def ll_insert(head, name, phone):
+    next_node = {'name': name, 'phone': phone, 'next': None}
+    if head is None: return next_node 
+
+    running = head
+    while running is not None:
+        if running['name'] == name:
+            running['phone'] = phone
+            return head
+        running = running['next']
+
+    running = head
+    while running['next'] is not None: running = running['next']
+    running['next'] = next_node
+    return head
+
+print('======== TESTING LL_INSERT ==========')
+Name = ['Dima', 'Ivan', 'Maxim', 'Alex']
+
+for _ in range(10):
+    name = Name[rnd.randint(0, 3)]
+    phone = str(rnd.randint(0,9)) + str(rnd.randint(0,9)) + str(rnd.randint(0,9)) + '-' + \
+            str(rnd.randint(0,9)) + str(rnd.randint(0,9)) + str(rnd.randint(0,9)) 
+    print(name, phone)
+    head = ll_insert(head, name, phone)
+    print(head)
+    print('-----------------------------------\n')
+
+print('======== END TESTING ================')