[SOLVED] Drupal Preprocess/Hook Confusion

Drupal Preprocess/Hook Confusion

I'm having difficulty fully grasping the semantics in implementing hook themes, and consequently understanding the way in which preprocess/process functions are created. I'm using "The Definitive Guide to Drupal 7", which states(technically) that the following code should implement/define/ and output a theme function.

/**
* Implements hook_theme().
**/

<?php
// core/module_urtheme() - kiwi is the themesname
function node_kiwi(){
return array(
'addBlock' => array(
   'block' => 'content'
  ),
);
}
//define theme_functionName/ should it be theme_addBlocK?
function kiwi_addBlock($block){
return '<div class="kiwi-block">'.$block.'</div>';}
//use
print theme('addBlock',$block)

My problem lies in my utter confusion in regards to the syntax preprocess functions have:

 <?php 
 /** 
  * Implements template_preprocess_THEMEHOOK(). 
  */ 
  function HOOK_preprocess_THEMEHOOK(&$variables) { 
  // Changes go here. 
  }

Ultimately I'm aware both HOOK and THEMEHOOK are placeholders, but what should replace them, for HOOK the module/template/theme? For THEMEHOOK - the function's name/the theme/? I tried comparing the the theme hook implementation above, but it just made me more confused. I apologize in advance for any naive mistakes I might have made/said. Any and all help will be much appreciated :) .

Solution

As far as I know, HOOK is the name of the module or theme, and THEMEHOOK is the hook defined inside hook_theme(), the typical ones are "block", "node"... etc. For example: Yourmodule_preprocess_node(&$variables).