(CommandList
  children: [
    (Assignment
      keyword: Assign_None
      pairs: [(assign_pair lhs:(LhsName name:tid) op:Equal rhs:{(DQ ('yes pipe head'))} spids:[7])]
      spids: [7]
    )
    (ForEach
      iter_name: p
      iter_words: [{(${ VSub_Name SSH_PROTOCOLS)}]
      do_arg_iter: False
      body: 
        (DoGroup
          children: [
            (Assignment
              keyword: Assign_None
              pairs: [
                (assign_pair
                  lhs: (LhsName name:lines)
                  op: Equal
                  rhs: 
                    {
                      (CommandSubPart
                        command_list: 
                          (CommandList
                            children: [
                              (Pipeline
                                children: [
                                  (C {(${ VSub_Name SSH)} {(-) ($ VSub_Name '$p')} {(-F)} 
                                    {($ VSub_Name '$OBJ') (/ssh_proxy)} {(thishost)} {(SQ <'sh -c "while true;do echo yes;done | _POSIX2_VERSION=199209 head -2000"'>)}
                                  )
                                  (Subshell
                                    child: 
                                      (CommandList
                                        children: [
                                          (Sentence
                                            child: (C {(sleep)} {(3)})
                                            terminator: <Op_Semi ';'>
                                          )
                                          (C {(wc)} {(-l)})
                                        ]
                                      )
                                    spids: [49 59]
                                  )
                                ]
                                negated: False
                              )
                            ]
                          )
                        left_token: <Left_Backtick '`'>
                        spids: [28 60]
                      )
                    }
                  spids: [27]
                )
              ]
              spids: [27]
            )
            (If
              arms: [
                (if_arm
                  cond: [
                    (Sentence
                      child: 
                        (C {(Lit_Other '[')} {($ VSub_QMark '$?')} {(-ne)} {(0)} {(Lit_Other ']')})
                      terminator: <Op_Semi ';'>
                    )
                  ]
                  action: [
                    (C {(fail)} {(DQ ('yes|head test failed'))})
                    (Sentence
                      child: (C {(lines)} {(Lit_Other '=')} {(0)})
                      terminator: <Op_Semi ';'>
                    )
                  ]
                  spids: [-1 76]
                )
              ]
              spids: [-1 94]
            )
            (If
              arms: [
                (if_arm
                  cond: [
                    (Sentence
                      child: 
                        (C {(Lit_Other '[')} {($ VSub_Name '$lines')} {(-ne)} {(2000)} {(Lit_Other ']')})
                      terminator: <Op_Semi ';'>
                    )
                  ]
                  action: [
                    (C {(fail)} 
                      {(DQ ('yes|head returns ') ($ VSub_Name '$lines') (' lines instead of 2000'))}
                    )
                  ]
                  spids: [-1 110]
                )
              ]
              spids: [-1 122]
            )
          ]
          spids: [24 124]
        )
      spids: [18 22]
    )
  ]
)