# Null object

The absence of a value is represented by *nil*

```ruby
var undefined          # initialized with an implicit nil
say undefined==nil     # true
say defined(nil)       # false
```

However, *nil* is not an object, so we can't call methods on it. Alternatively, Sidef provides the *null* object:

```ruby
var null_obj = null         # initialize with a null value
say null_obj.is_a(null)     # true
say defined(null_obj)       # true
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://trizen.gitbook.io/sidef-lang/programming_tasks/n/null_object.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.