[Term Entry] Dart Queue: .addFirst()

content/dart/concepts/queue/terms/addFirst/addFirst.md

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+---
+Title: '.addFirst()'
+Description: 'Adds an element at the beginning of a queue.'
+Subjects:
+  - 'Code Foundations'
+  - 'Computer Science'
+Tags:
+  - 'Dart'
+  - 'Queues'
+  - 'Methods'
+CatalogContent:
+  - 'learn-dart'
+  - 'paths/computer-science'
+---
+
+In Dart, the **`.addFirst()`** method inserts an element at the front of a `Queue`. Existing elements are shifted back, and the newly added element becomes the first item in the queue. This method is part of the `Queue` class under the `dart:collection` library.
+
+## Syntax
+
+```pseudo
+queue.addFirst(element);
+```
+
+**Parameters:**
+
+- `element`: The element to add to the front of the queue
+
+**Return value:**
+
+This method does not return a value (`void`).
+
+## Example
+
+The following example demonstrates the usage of the `.addFirst()` method:
+
+```dart
+import 'dart:collection';
+
+void main() {
+  Queue<int> numbers = Queue<int>();
+  numbers.add(20);
+  numbers.add(30);
+  numbers.add(40);
+
+  print("Original queue: $numbers");
+
+  numbers.addFirst(10);
+  print("After addFirst(10): $numbers");
+
+  numbers.addFirst(5);
+  print("After addFirst(5): $numbers");
+}
+```
+
+The output for the above code is as follows:
+
+```shell
+Original queue: {20, 30, 40}
+After addFirst(10): {10, 20, 30, 40}
+After addFirst(5): {5, 10, 20, 30, 40}
+```