Mention usage of empty and EmptyDrop

_basics/types.md

@@ -3,13 +3,14 @@ title: Types
 description: An overview of data types in the Liquid template language.
 ---
 
-Liquid objects can have one of five types:
+Liquid objects can be one of six types:
 
 - [String](#string)
 - [Number](#number)
 - [Boolean](#boolean)
 - [Nil](#nil)
 - [Array](#array)
+- [EmptyDrop](#emptydrop)
 
 You can initialize Liquid variables with the [assign]({{ "/tags/variable/#assign" | prepend: site.baseurl }}) or [capture]({{ "/tags/variable/#capture" | prepend: site.baseurl }}) tags.
 
@@ -124,3 +125,31 @@ Adam
 You cannot initialize arrays using only Liquid.
 
 You can, however, use the [split]({{ "/filters/split/" | prepend: site.baseurl }}) filter to break a string into an array of substrings.
+
+## EmptyDrop
+
+An EmptyDrop object is returned if you try to access a deleted object. In the example below, `page_1`, `page_2` and `page_3` are all EmptyDrop objects:
+
+```liquid
+{% raw %}
+{% assign variable = "hello" %}
+{% assign page_1 = pages[variable] %}
+{% assign page_2 = pages["does-not-exist"] %}
+{% assign page_3 = pages.this-handle-does-not-exist %}
+{% endraw %}
+```
+
+### Checking for emptiness
+
+You can check to see if an object exists or not before you access any of its attributes.
+
+```liquid
+{% raw %}
+{% unless pages == empty %}
+  <h1>{{ pages.frontpage.title }}</h1>
+  <div>{{ pages.frontpage.content }}</div>
+{% endunless %}
+{% endraw %}
+```
+
+Both empty strings and empty arrays will return `true` if checked for equivalence with `empty`.