Parse doesn't work for insertion after last line of some keyword

Question

I want to insert new sentence under last line where keyword is found, but it doesn't work, seems simple at first:

    source: {
        bla bla bla bla
        bla bla bla bla
        bla bla keyword bla bla
        bla bla keyword bla bla
        bla bla keyword bla bla

        bla bla bla bla
        bla bla bla bla
        bla bla bla bla
    }

    rules: [
        some [
            thru "keyword" to newline skip
        ]
        mark: ([insert mark "stranger"]) 
        to end
    ]

    parse source rules

Answer 1

Your block evaluates to the same block. You have to use

mark: (insert mark "stranger") 

without the block.

And don't use source as source is already defined as a mezzanine function.