ASM Support ID in HTTP Header

I have been working on this again recently as I had previously stopped working on it and found that the way I could get this working was to use the following iRule.

when HTTP_REQUEST_RELEASE {
     check if we have collected the support id ok and if so add the HTTP header
    if {[info exists x_asm_support_id]} {
        HTTP::header insert X-ASM-SUPPORT-ID $x_asm_support_id
    }
}

when ASM_REQUEST_DONE {
     Collect the Support ID and store it so we can add it to a HTTP header
    set x_asm_support_id [ASM::support_id]
}