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+# Custom extension
+
+This module provides a simple implementation for icons that are bundled in your application resources using custom `DelimiterProcessor`. It can be used as a reference when dealing with new functionality based on _delimiters_. 
+
+```markdown
+# Hello @ic-android-black-24
+
+**Please** click @ic-home-green-24 (home icon) if you want to go home.
+```
+
+Here we will substitute elements starting with `@ic-` for icons that we have in our resources:
+
+* `@ic-android-black-24` -> `R.drawable.ic_android_black_24dp`
+* `@ic-home-green-24` -> `R.drawable.ic_home_green_24dp`
+
+In order to provide reliable parsing we need to have delimiters _around_ desired content. So, `@ic-home-green-24` would become `@ic-home-green-24@`. This is current limitation of [commonmark-java](https://github.com/atlassian/commonmark-java) library that Markwon uses underneath. There is an ongoing [issue](https://github.com/atlassian/commonmark-java/issues/113) that might change this in future thought.
+
+But as we known the pattern beforehand it's pretty easy to pre-process raw markdown and make it the way we want it. Please refer to `IconProcessor#process` method for the reference.
+
+So, the our steps would be:
+
+* prepare raw markdown (wrap icons with `@` if it's not already)
+* construct a Parser with our registered delimiter processor
+* parse markdown and obtain a `Node`
+* create a node visitor that will additionally visit custom node (`IconNode`)
+* use markdown