Regex Tester & Validator

This PCRE regex matches configuration or assignment lines formatted as `text = '...'` where the quoted value does not contain the string 'item_1' optionally followed by a comma. It utilizes a conditional lookahead to capture the contents of the string only if the specified item is absent. This is particularly useful in scenarios where you need to verify that a specific value is not already present in a comma-separated list before safely appending it.