     ecmd: (explain, cmd)->
         explain ?= null
         cmd ?= null
-        $ =
+        $$ =
             node: 'ecmd'
             explain: explain
             cmd: cmd
     explain: (explain, queryPlan)->
-        $ =
+        $$ =
             node: 'explain'
             explain: explain
             queryPlan: queryPlan

    cmd:
        vacuum: (nm)->
            nm ?= null
            $ =
                node: 'cmd'
                type: 'vacuum'
                nm: nm
        begin_trans: (transtype, trans_opt)->
            $ =
                node: 'begin_trans'
                transtype: transtype
                trans_opt: trans_opt
        commit_trans: (trans_opt)->
            $ =
                node: 'commit_trans'
                trans_opt: trans_opt
        end_trans: (trans_opt)->
            $ =
                node: 'end_trans'
                trans_opt: trans_opt
        reindex: (nm, dbnm)->
            nm ?= null
            dbnm ?= null
            $ =
                node: 'reindex'
                nm: nm
                dbnm: dbnm

            terminal: terminal

    dbnm: (nm)->
        $$ =
            node: 'dbnm'
            nm: nm

    trans_opt: (nm)->
        nm ?= null
        $$ =
            node: 'trans_opt'
            value: nm

    transtype: (type)->
        type ?= null
        $$ =
            node: 'transtype'
            type: type

