variable token

    variable token

    # The token should be unguessable by the user.
    set token [binary format {iu1 f1 iu1} \
        $renders \
        [expr rand()] \
        [zlib crc32 $content] \
    ]

    variable token
    # Pass through already processed content marked with the
    # token.
    set tokenLen [string length $token]
    if {[string range $content 0 $tokenLen-1] eq $token} {
        return $content
    }

        return [list text $content]

        return [node text $content]

    return $r

    return [node tree $r]

proc tclmark::node {tag args} {
    variable token

proc tclmark::flatten tree {
    if {[llength $tree] != 2} {
        error [list not two elements: $tree]

    list $token $tag $args
}
proc tclmark::flatten node {
    variable token
    if {[llength $node] != 3} {
        error [list not three elements: $node]

    lassign $tree tag data

    lassign $node nodeToken tag data
    if {$nodeToken ne $token} {
        error [list invalid token in $node]
    }

            lindex $data

            lindex $data 0

            entities $data

            entities [lindex $data 0]

proc tclmark::tree args {
    list tree $args
}

    tree {html <b>} [msubst $content] {html </b>}

    node tree [node html <b>] [msubst $content] [node html </b>]

    tree {html <i>} [msubst $content] {html </i>}

    node tree [node html <i>] [msubst $content] [node html </i>]