(command.CommandList
  children: [
    (C {<echo>} {(DQ <Start>)})
    (command.ShFunction
      name: sub
      body: 
        (BraceGroup
          children: [
            (C {<echo>} {($ Id.VSub_At '$@')})
            (C {<echo>} {(DQ <1>)})
            (C {<echo>} {(DQ <2>)})
            (C {<echo>} {(DQ <3>)})
          ]
        )
    )
    (C {<sub>} {<arg>})
    (C {<echo>} {(DQ <'Stop!'>)})
  ]
)