Function zp_filter_unique_id

Build Unique ID for storage and retrieval.

Simply using a function name is not enough, as several functions can have the same name when they are enclosed in classes.

global array $_zp_filters storage for all of the filters

Package: functions
Author: Ozh
Located at functions-filter.php

Parameters summary
`string`	`$hook`	hook to which the function is attached
`string\|array`	`$function`	used for creating unique id
`integer\|boolean`	`$priority`	used in counting how many hooks were applied. If === false and $function is an object reference, we return the unique id only if it already has one, false otherwise.
`string`	`$type,…`	filter or action

Return value summary
`string`	unique ID for usage as array key