(command.CommandList
  children: [
    (C {<echo>} {(SQ <'--- pgrphack insists on an argument'>)})
    (command.CommandList
      children: [
        (command.Sentence child:(C {<pgrphack>}) terminator:<Id.Op_Semi _>)
        (C {<echo>} {($ Id.VSub_QMark '$?')})
      ]
    )
    (C {<echo>} {(SQ <'--- pgrphack complains if it cannot run program'>)})
    (command.CommandList
      children: [
        (command.Sentence
          child: (C {<pgrphack>} {<'./nonexistent'>})
          terminator: <Id.Op_Semi _>
        )
        (C {<echo>} {($ Id.VSub_QMark '$?')})
      ]
    )
    (C {<echo>} {(SQ <'--- pgrphack runs a program'>)})
    (command.CommandList
      children: [
        (command.Sentence child:(C {<pgrphack>} {<echo>} {<ok>}) terminator:<Id.Op_Semi _>)
        (C {<echo>} {($ Id.VSub_QMark '$?')})
      ]
    )
  ]
)