[sync] I need API functions

[Anthony Mills]

How do I write these functions?  What source should I look into?

function import($content, $contenttype) //returns $guid false if fails
//called by $registry->call($type . '/import', array($content, 
$contenttype))

function export($guid, $contenttype) //returns $content false if fails
//called by $registry->call($type . '/export', array($content, 
$contenttype))

function remove($guid) //returns true/false?  this one may exist
//called by $registry->call($type . '/import', array($content, 
$contenttype))

function replace($guid, $content, $contenttype) //returns true/false
//called by $registry->call($type . '/replace', array($guid, $content, 
$contenttype));

function listBy($timestamp, 'change'|'add'|'delete');  //returns an 
array of $guids false if fails
//called by $registry->call($type . '/listBy', array($timestamp, $listtype))

Anthony