Added an add at position subroutiune to linked list

CONTRIBUTING.md

@@ -1,4 +1,4 @@
-# Contributing guidelines
+<!-- # Contributing guidelines -->
 
 ## Before contributing
 

data_structures/linked_list/__init__.py

@@ -21,8 +21,45 @@ def __init__(self) -> None:
         self.head: Node | None = None
         self.size = 0
 
-    def add(self, item: Any) -> None:
-        self.head = Node(item, self.head)
+    def add(self, item: Any, position: int = 0) -> None:
+        """
+        Add an item to the LinkedList at the specified position.
+        Default position is 0 (the head).
+
+        Args:
+            item (Any): The item to add to the LinkedList.
+            position (int, optional): The position at which to add the item.
+            Defaults to 0.
+
+        Raises:
+            ValueError: If the position is negative.
+
+        >>> linked_list = LinkedList()
+        >>> linked_list.add(1)
+        >>> linked_list.add(2)
+        >>> linked_list.add(3)
+        >>> linked_list.add(4, 2)
+        >>> print(linked_list)
+        3 --> 2 --> 4 --> 1
+        """
+        if position < 0:
+            raise ValueError("Position must be non-negative")
+
+        if position == 0 or self.head is None:
+            new_node = Node(item, self.head)
+            self.head = new_node
+        else:
+            current = self.head
+            counter = 0
+            while current and counter < position - 1:
+                current = current.next
+                counter += 1
+
+            if current:  # Check if current is not None
+                new_node = Node(item, current.next)
+                current.next = new_node
+            else:
+                raise ValueError("Out of bounds")
         self.size += 1
 
     def remove(self) -> Any: