WIP: please feel free to add more examples or comments here

a blue link `[[Page_On_This_Wiki#Introduction|The intro]]`:
* link_type: page
* page_namespace: 0
* page_title: Page_On_This_Wiki
* is_redirect: false
* fragment: Introduction
* page_id: 123

a blue link to a redirect `[[A_Redirect_To_Page_On_This_Wiki#Endtroducing]]`:
* link_type: page
* page_namespace: 0
* page_title: A_Redirect_To_Page_On_This_Wiki
* is_redirect: true
* fragment: Endtroducing
* page_id: 231

a red link `[[A_Non_Existing_Page_On_This_Wiki#Introduction]]`:
* link_type: page
* page_namespace: 0
* page_title: A_Non_Existing_Page_On_This_Wiki
* is_redirect: false
* fragment: Introduction

a template link `{{A_Template|params}}`:
* link_type: template
* page_namespace: 10
* page_title: A_Template

a category link `[[Category:A_Category]]`:
* link_type: category
* page_namespace: 14
* page_title: A_Category

a language link [[:ko:Page_On_A_Sister_Language_Wiki_In_Korean#Introduction]]
* link_type: language
* page_title: Page_On_A_Sister_Language_Wiki_In_Korean
* fragment: Introduction
* iw_prefix: ko

a interwiki link to a local project `[[:mw:Help:MediaWiki#QuickStart]]`:
* link_type: interwiki
* page_title: Help:MediaWiki (here the page_title contains the namespace prefix)
* fragment: QuickStart
* iw_prefix: mw

a interwiki link to an external site known as site1 in the interwiki database `[[site1:a_page/on_a_website]]`:
* link_type: interwiki
* page_title: a_page/on_a_website
* iw_prefix: site1

a media link to commons: e.g. `[[File:An_Image_On_Commons.jpg]]`
* link_type: media
* page_title: An_Image_On_Commons.jpg

a media link to a locally uploaded media: `[[File:An_Image_Uploaded_Locally.jpg]]` (ouch! how do we distinguish those? do we care?)
* link_type: media
* page_title: An_Image_Uploaded_Locally.jpg

an external link `[https://wikipedia.org/a_page#fragment wikipedia]`:
* link_type: external
* external_url: https://wikipedia.org/a_page
* fragment: fragment