(command.CommandList
  children: [
    (command.If
      arms: [
        (if_arm
          cond: [
            (command.Sentence
              child: 
                (C {(Lit_LBracket '[')} {(DQ ($ VSub_DollarName '$SSH_CLIENT'))} {(Lit_RBracket ']')})
              terminator: <Op_Semi ';'>
            )
          ]
          action: [
            (command.ShAssignment
              pairs: [
                (assign_pair
                  lhs: (sh_lhs_expr.Name name:expression)
                  op: Equal
                  rhs: 
                    {
                      (command_sub
                        left_token: <Left_DollarParen '$('>
                        command_list: 
                          (command.CommandList
                            children: [
                              (command.Pipeline
                                children: [
                                  (C {(echo)} {(DQ ($ VSub_DollarName '$SSH_CLIENT'))})
                                  (C {(sed)} 
                                    {
                                      (SQ <'s/.*://;\n'> 
                                        <
'         s/^\\([0-9.]*\\) [0-9]* \\([0-9]*\\)$/not \\( host \\1 and port \\2 \\)/'
                                        >
                                      )
                                    }
                                  )
                                ]
                                negated: F
                              )
                            ]
                          )
                      )
                    }
                )
              ]
            )
          ]
        )
      ]
    )
    (C {(tcpdump)} {(DQ ($ VSub_At '$@'))} {($ VSub_DollarName '$expression')})
  ]
)