parse
    "comment stating purpose of message"
    |result a x tmp error res t node top toAdd g|
    error := false.
    t := Tree new.
    t tag: (NonTerm g).
    g := Tree new.
    g tag: (CTerm eop).
    mag := {{NonTerm g. t.}. {CTerm eop. g.}.}.
    result := OrderedCollection new.
    a := (scanner nextToken) tag.
    x := ((mag at: 1) at: 1).
    [(x ~= (CTerm eop) and: (error not))] whileTrue:[
        x := ((mag at: 1) at:1).
        top := ((mag at: 1) at:2).
        (terms includes: x) ifTrue: [
            ((x = CTerm pass) or: (x = a )) ifTrue: [
                node := Tree new.
                node tag: x.
                (top childs) add: node.
                (x = CTerm pass) ifTrue:[
                    mag := mag allButFirst.
                ].
                (x = a) ifTrue:[
                    mag := mag allButFirst.
                    a := (scanner nextToken) tag.
                ]
            ]
            ifFalse: [
                Transcript show: 'ERROR'.
                error := true.
            ].
        ]
        ifFalse:[
            tmp := (table at:(x-20)) at:a.
            (tmp at:1) = -1
            ifTrue: [
                Transcript show: 'ERROR'.
                error := true.
            ]
            ifFalse: [
                node := Tree new.
                node tag: x.
                (top childs) add:node.
                mag := mag allButFirst.
                "mag := tmp, mag."
                toAdd := {}.
                (tmp reverse) do: [:object | toAdd := {{object. node.}.},toAdd].
                mag := toAdd,mag.
                res := (self class describe: x), ' -> '.
                tmp do: [:object | res := res, ' ', (self class describe: object), ', ' ].
                result add:res.
            ].
        ].
    ].
    t describe:'-'.
    "error ifFalse:[
        result do: [:object | Transcript show: object; cr].
]"