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                    ('                 -Q              # use queue insert as start time\n')
                    ('                 -s              # include start time of I/O (s)\n')
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                    ('                 -h              # this usage message\n')
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                    ('       iosnoop                   # watch block I/O live (unbuffered)\n')
                    ('       iosnoop 1                 # trace 1 sec (buffered)\n')
                    ('       iosnoop -Q                # include queueing time in LATms\n')
                    ('       iosnoop -ts               # include start and end timestamps\n')
                    ("       iosnoop -i '*R*'          # trace reads\n")
                    ('       iosnoop -p 91             # show I/O issued when PID 91 is on-CPU\n')
                    ('       iosnoop -Qp 91            # show I/O queued by PID 91, queue time\n')
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                    ('See the man page and example file for more info.\n')
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                      token: (Token id:Id.Lit_EscapedChar val:'\\"' span_id:763)
                    )
                  )
                }
              spids: [758]
            )
          ]
        )
      ]
    )
    (command.If
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            (command.Sentence
              child: 
                (command.DParen
                  child: 
                    (arith_expr.VarRef
                      token: (Token id:Id.Lit_ArithVarLike val:opt_duration span_id:770)
                    )
                )
              terminator: (Token id:Id.Op_Semi val:';' span_id:774)
            )
          ]
          action: [
            (C {(echo)} 
              {
                (DQ ('Tracing block I/O') ($ Id.VSub_DollarName '$ftext') (' for ') 
                  ($ Id.VSub_DollarName '$duration') (' seconds (buffered)...')
                )
              }
            )
          ]
          spids: [766 776]
        )
      ]
      else_action: [
        (C {(echo)} {(DQ ('Tracing block I/O') ($ Id.VSub_DollarName '$ftext') ('. Ctrl-C to end.'))})
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    (command.If
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        (if_arm
          cond: [
            (command.Sentence
              child: 
                (command.DParen
                  child: 
                    (arith_expr.VarRef
                      token: (Token id:Id.Lit_ArithVarLike val:opt_queue span_id:806)
                    )
                )
              terminator: (Token id:Id.Op_Semi val:';' span_id:810)
            )
          ]
          action: [
            (command.ShAssignment
              pairs: [
                (assign_pair
                  lhs: (sh_lhs_expr.Name name:b_start)
                  op: assign_op.Equal
                  rhs: {(block_rq_insert)}
                  spids: [815]
                )
              ]
            )
          ]
          spids: [802 812]
        )
      ]
      else_action: [
        (command.ShAssignment
          pairs: [
            (assign_pair
              lhs: (sh_lhs_expr.Name name:b_start)
              op: assign_op.Equal
              rhs: {(block_rq_issue)}
              spids: [821]
            )
          ]
        )
      ]
    )
    (command.AndOr
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        (command.DParen
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        )
        (command.ShAssignment
          pairs: [
            (assign_pair
              lhs: (sh_lhs_expr.Name name:use)
              op: assign_op.Equal
              rhs: {(mawk)}
              spids: [839]
            )
          ]
        )
        (command.ShAssignment
          pairs: [
            (assign_pair
              lhs: (sh_lhs_expr.Name name:use)
              op: assign_op.Equal
              rhs: {(gawk)}
              spids: [844]
            )
          ]
        )
      ]
    )
    (command.AndOr
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      children: [
        (command.DBracket
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            (bool_expr.Unary
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              child: {(/usr/bin/) ($ Id.VSub_DollarName '$use')}
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        )
        (command.ShAssignment
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            (assign_pair
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              op: assign_op.Equal
              rhs: {($ Id.VSub_DollarName '$use')}
              spids: [861]
            )
          ]
        )
        (command.ShAssignment
          pairs: [
            (assign_pair
              lhs: (sh_lhs_expr.Name name:awk)
              op: assign_op.Equal
              rhs: {(awk)}
              spids: [866]
            )
          ]
        )
      ]
    )
    (command.ShAssignment
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        (assign_pair
          lhs: (sh_lhs_expr.Name name:wroteflock)
          op: assign_op.Equal
          rhs: {(1)}
          spids: [869]
        )
      ]
    )
    (command.AndOr
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      children: [
        (C {(cd)} {($ Id.VSub_DollarName '$tracing')})
        (C {(die)} 
          {
            (DQ ('ERROR: accessing tracing. Root user? Kernel has FTRACE?\n') 
              ('    debugfs mounted? (mount -t debugfs debugfs /sys/kernel/debug)')
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          }
        )
      ]
    )
    (command.AndOr
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      children: [
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        (C {(die)} 
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            (DQ ('ERROR: ftrace may be in use by PID ') 
              (command_sub
                left_token: (Token id:Id.Left_DollarParen val:'$(' span_id:907)
                command_list: 
                  (command.CommandList
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                  )
              ) (' ') ($ Id.VSub_DollarName '$flock')
            )
          }
        )
      ]
    )
    (command.AndOr
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      children: [
        (command.Simple
          words: [{(echo)} {($ Id.VSub_Dollar '$$')}]
          redirects: [
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              op: (Token id:Id.Redir_Great val:'>' span_id:920)
              fd: -1
              arg_word: {($ Id.VSub_DollarName '$flock')}
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          ]
        )
        (C {(die)} {(DQ ('ERROR: unable to write ') ($ Id.VSub_DollarName '$flock') (.))})
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    (command.Simple
      words: [{(echo)} {(nop)}]
      redirects: [
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          op: (Token id:Id.Redir_Great val:'>' span_id:942)
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    (C {(warn)} {(DQ ('echo ') ($ Id.VSub_DollarName '$bufsize_kb') (' > buffer_size_kb'))})
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          spids: [954]
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              terminator: (Token id:Id.Op_Semi val:';' span_id:964)
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                    {
                      (DQ ('rwbs ~ ') 
                        (word_part.EscapedLiteral
                          token: (Token id:Id.Lit_EscapedChar val:'\\"' span_id:972)
                        ) ($ Id.VSub_DollarName '$iotype') 
                        (word_part.EscapedLiteral
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                        )
                      )
                    }
                  spids: [969]
                )
              ]
            )
          ]
          spids: [956 966]
        )
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                (command.DParen
                  child: 
                    (arith_expr.VarRef
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                )
              terminator: (Token id:Id.Op_Semi val:';' span_id:987)
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          ]
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                )
                (command.ShAssignment
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                      spids: [1007]
                    )
                  ]
                )
              ]
            )
            (command.ShAssignment
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                (assign_pair
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                  op: assign_op.Equal
                  rhs: {(DQ (${ Id.VSub_Name filter) ('dev == ') ($ Id.VSub_DollarName '$dev'))}
                  spids: [1014]
                )
              ]
            )
          ]
          spids: [979 989]
        )
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    )
    (command.ShAssignment
      pairs: [
        (assign_pair
          lhs: (sh_lhs_expr.Name name:filter_i)
          op: assign_op.Equal
          rhs: {($ Id.VSub_DollarName '$filter')}
          spids: [1025]
        )
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    )
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            (command.Sentence
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                (command.DParen
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                    (arith_expr.VarRef
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                    )
                )
              terminator: (Token id:Id.Op_Semi val:';' span_id:1036)
            )
          ]
          action: [
            (command.AndOr
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              children: [
                (command.DBracket
                  expr: 
                    (bool_expr.Binary
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                      right: {(DQ )}
                    )
                )
                (command.ShAssignment
                  pairs: [
                    (assign_pair
                      lhs: (sh_lhs_expr.Name name:filter_i)
                      op: assign_op.Equal
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                      spids: [1056]
                    )
                  ]
                )
              ]
            )
            (command.ShAssignment
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                (assign_pair
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                  op: assign_op.Equal
                  rhs: 
                    {(DQ (${ Id.VSub_Name filter_i) ('common_pid == ') ($ Id.VSub_DollarName '$pid'))}
                  spids: [1063]
                )
              ]
            )
            (command.AndOr
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              children: [
                (command.DBracket
                  expr: 
                    (bool_expr.Binary
                      op_id: Id.BoolBinary_GlobDEqual
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                      right: {(DQ )}
                    )
                )
                (command.ShAssignment
                  pairs: [
                    (assign_pair
                      lhs: (sh_lhs_expr.Name name:filter)
                      op: assign_op.Equal
                      rhs: {(0)}
                      spids: [1088]
                    )
                  ]
                )
              ]
            )
          ]
          spids: [1028 1038]
        )
      ]
    )
    (command.If
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        (if_arm
          cond: [
            (command.Sentence
              child: 
                (command.DParen
                  child: 
                    (arith_expr.Binary
                      op_id: Id.Arith_DPipe
                      left: 
                        (arith_expr.Binary
                          op_id: Id.Arith_DPipe
                          left: 
                            (arith_expr.VarRef
                              token: (Token id:Id.Lit_ArithVarLike val:opt_iotype span_id:1097)
                            )
                          right: 
                            (arith_expr.VarRef
                              token: (Token id:Id.Lit_ArithVarLike val:opt_device span_id:1101)
                            )
                        )
                      right: 
                        (arith_expr.VarRef
                          token: (Token id:Id.Lit_ArithVarLike val:opt_pid span_id:1105)
                        )
                    )
                )
              terminator: (Token id:Id.Op_Semi val:';' span_id:1109)
            )
          ]
          action: [
            (command.If
              arms: [
                (if_arm
                  cond: [
                    (command.AndOr
                      ops: [Id.Op_DPipe]
                      children: [
                        (command.Pipeline
                          children: [
                            (command.Simple
                              words: [{(echo)} {(DQ ($ Id.VSub_DollarName '$filter_i'))}]
                              redirects: [
                                (redir.Redir
                                  op: (Token id:Id.Redir_Great val:'>' span_id:1124)
                                  fd: -1
                                  arg_word: 
                                    {(events/block/) ($ Id.VSub_DollarName '$b_start') (/filter)}
                                )
                              ]
                            )
                          ]
                          negated: T
                        )
                        (command.Pipeline
                          children: [
                            (command.Simple
                              words: [{(echo)} {(DQ ($ Id.VSub_DollarName '$filter'))}]
                              redirects: [
                                (redir.Redir
                                  op: (Token id:Id.Redir_Great val:'>' span_id:1142)
                                  fd: -1
                                  arg_word: {(events/block/block_rq_complete/filter)}
                                )
                              ]
                            )
                          ]
                          negated: T
                        )
                      ]
                    )
                  ]
                  action: [(C {(edie)} {(DQ ('ERROR: setting -d or -t filter. Exiting.'))})]
                  spids: [1114 1147]
                )
              ]
            )
          ]
          spids: [1093 1111]
        )
      ]
    )
    (command.If
      arms: [
        (if_arm
          cond: [
            (command.Sentence
              child: 
                (command.AndOr
                  ops: [Id.Op_DPipe]
                  children: [
                    (command.Pipeline
                      children: [
                        (command.Simple
                          words: [{(echo)} {(1)}]
                          redirects: [
                            (redir.Redir
                              op: (Token id:Id.Redir_Great val:'>' span_id:1169)
                              fd: -1
                              arg_word: {(events/block/) ($ Id.VSub_DollarName '$b_start') (/enable)}
                            )
                          ]
                        )
                      ]
                      negated: T
                    )
                    (command.Pipeline
                      children: [
                        (command.Simple
                          words: [{(echo)} {(1)}]
                          redirects: [
                            (redir.Redir
                              op: (Token id:Id.Redir_Great val:'>' span_id:1185)
                              fd: -1
                              arg_word: {(events/block/block_rq_complete/enable)}
                            )
                          ]
                        )
                      ]
                      negated: T
                    )
                  ]
                )
              terminator: (Token id:Id.Op_Semi val:';' span_id:1188)
            )
          ]
          action: [(C {(edie)} {(DQ ('ERROR: enabling block I/O tracepoints. Exiting.'))})]
          spids: [1161 1190]
        )
      ]
    )
    (command.AndOr
      ops: [Id.Op_DAmp]
      children: [
        (command.DParen
          child: (arith_expr.VarRef token:(Token id:Id.Lit_ArithVarLike val:opt_start span_id:1203))
        )
        (C {(printf)} {(DQ ('%-15s '))} {(DQ (STARTs))})
      ]
    )
    (command.AndOr
      ops: [Id.Op_DAmp]
      children: [
        (command.DParen
          child: (arith_expr.VarRef token:(Token id:Id.Lit_ArithVarLike val:opt_end span_id:1222))
        )
        (C {(printf)} {(DQ ('%-15s '))} {(DQ (ENDs))})
      ]
    )
    (C {(printf)} {(DQ ('%-12.12s %-6s %-4s %-8s %-12s %-6s %8s') (Id.Lit_Other '\\') (n))} {(DQ (COMM))} 
      {(DQ (PID))} {(DQ (TYPE))} {(DQ (DEV))} {(DQ (BLOCK))} {(DQ (BYTES))} {(DQ (LATms))}
    )
    (command.ShAssignment
      pairs: [
        (assign_pair
          lhs: (sh_lhs_expr.Name name:offset)
          op: assign_op.Equal
          rhs: 
            {
              (command_sub
                left_token: (Token id:Id.Left_DollarParen val:'$(' span_id:1300)
                command_list: 
                  (command.CommandList
                    children: [
                      (C {($ Id.VSub_DollarName '$awk')} 
                        {
                          (SQ (Token id:Id.Lit_Chars val:'BEGIN { o = 0; }\n' span_id:1304) 
                            (Token
                              id: Id.Lit_Chars
                              val: '\t$1 == "#" && $2 ~ /TASK/ && NF == 6 { o = 1; }\n'
                              span_id: 1305
                            ) (Token id:Id.Lit_Chars val:'\t$2 ~ /TASK/ { print o; exit }' span_id:1306)
                          )
                        } {(trace)}
                      )
                    ]
                  )
              )
            }
          spids: [1299]
        )
      ]
    )
    (C {(warn)} {(DQ ('echo > trace'))})
    (command.Pipeline
      children: [
        (command.Subshell
          command_list: 
            (command.CommandList
              children: [
                (command.If
                  arms: [
                    (if_arm
                      cond: [
                        (command.Sentence
                          child: 
                            (command.DParen
                              child: 
                                (arith_expr.VarRef
                                  token: (Token id:Id.Lit_ArithVarLike val:opt_duration span_id:1328)
                                )
                            )
                          terminator: (Token id:Id.Op_Semi val:';' span_id:1332)
                        )
                      ]
                      action: [(C {(sleep)} {($ Id.VSub_DollarName '$duration')}) (C {(cat)} {(trace)})]
                      spids: [1324 1334]
                    )
                  ]
                  else_action: [(C {(cat)} {(trace_pipe)})]
                )
              ]
            )
        )
        (C {($ Id.VSub_DollarName '$awk')} {(-v)} 
          {(Id.Lit_VarLike 'o=') ($ Id.VSub_DollarName '$offset')} {(-v)} {(Id.Lit_VarLike 'opt_name=') ($ Id.VSub_DollarName '$opt_name')} {(-v)} 
          {(Id.Lit_VarLike 'name=') ($ Id.VSub_DollarName '$name')} {(-v)} {(Id.Lit_VarLike 'opt_duration=') ($ Id.VSub_DollarName '$opt_duration')} {(-v)} 
          {(Id.Lit_VarLike 'opt_start=') ($ Id.VSub_DollarName '$opt_start')} {(-v)} {(Id.Lit_VarLike 'opt_end=') ($ Id.VSub_DollarName '$opt_end')} {(-v)} 
          {(Id.Lit_VarLike 'b_start=') ($ Id.VSub_DollarName '$b_start')} 
          {
            (SQ (Token id:Id.Lit_Chars val:'\n' span_id:1409) 
              (Token id:Id.Lit_Chars val:'\t# common fields\n' span_id:1410) (Token id:Id.Lit_Chars val:'\t$1 != "#" {\n' span_id:1411) 
              (Token
                id: Id.Lit_Chars
                val: '\t\t# task name can contain dashes\n'
                span_id: 1412
              ) (Token id:Id.Lit_Chars val:'\t\tcomm = pid = $1\n' span_id:1413) 
              (Token
                id: Id.Lit_Chars
                val: '\t\tsub(/-[0-9][0-9]*/, "", comm)\n'
                span_id: 1414
              ) (Token id:Id.Lit_Chars val:'\t\tsub(/.*-/, "", pid)\n' span_id:1415) 
              (Token
                id: Id.Lit_Chars
                val: '\t\ttime = $(3+o); sub(":", "", time)\n'
                span_id: 1416
              ) (Token id:Id.Lit_Chars val:'\t\tdev = $(5+o)\n' span_id:1417) 
              (Token id:Id.Lit_Chars val:'\t}\n' span_id:1418) (Token id:Id.Lit_Chars val:'\n' span_id:1419) 
              (Token id:Id.Lit_Chars val:'\t# block I/O request\n' span_id:1420) (Token id:Id.Lit_Chars val:'\t$1 != "#" && $0 ~ b_start {\n' span_id:1421) 
              (Token
                id: Id.Lit_Chars
                val: '\t\tif (opt_name && match(comm, name) == 0)\n'
                span_id: 1422
              ) (Token id:Id.Lit_Chars val:'\t\t\tnext\n' span_id:1423) 
              (Token id:Id.Lit_Chars val:'\t\t#\n' span_id:1424) 
              (Token
                id: Id.Lit_Chars
                val: '\t\t# example: (fields1..4+o) 202,1 W 0 () 12862264 + 8 [tar]\n'
                span_id: 1425
              ) 
              (Token
                id: Id.Lit_Chars
                val: '\t\t# The cmd field "()" might contain multiple words (hex),\n'
                span_id: 1426
              ) (Token id:Id.Lit_Chars val:'\t\t# hence stepping from the right (NF-3).\n' span_id:1427) 
              (Token id:Id.Lit_Chars val:'\t\t#\n' span_id:1428) (Token id:Id.Lit_Chars val:'\t\tloc = $(NF-3)\n' span_id:1429) 
              (Token id:Id.Lit_Chars val:'\t\tstarts[dev, loc] = time\n' span_id:1430) (Token id:Id.Lit_Chars val:'\t\tcomms[dev, loc] = comm\n' span_id:1431) 
              (Token id:Id.Lit_Chars val:'\t\tpids[dev, loc] = pid\n' span_id:1432) (Token id:Id.Lit_Chars val:'\t\tnext\n' span_id:1433) (Token id:Id.Lit_Chars val:'\t}\n' span_id:1434) 
              (Token id:Id.Lit_Chars val:'\n' span_id:1435) (Token id:Id.Lit_Chars val:'\t# block I/O completion\n' span_id:1436) 
              (Token
                id: Id.Lit_Chars
                val: '\t$1 != "#" && $0 ~ /rq_complete/ {\n'
                span_id: 1437
              ) (Token id:Id.Lit_Chars val:'\t\t#\n' span_id:1438) 
              (Token
                id: Id.Lit_Chars
                val: '\t\t# example: (fields1..4+o) 202,1 W () 12862256 + 8 [0]\n'
                span_id: 1439
              ) (Token id:Id.Lit_Chars val:'\t\t#\n' span_id:1440) 
              (Token id:Id.Lit_Chars val:'\t\tdir = $(6+o)\n' span_id:1441) (Token id:Id.Lit_Chars val:'\t\tloc = $(NF-3)\n' span_id:1442) 
              (Token id:Id.Lit_Chars val:'\t\tnsec = $(NF-1)\n' span_id:1443) (Token id:Id.Lit_Chars val:'\n' span_id:1444) 
              (Token
                id: Id.Lit_Chars
                val: '\t\tif (starts[dev, loc] > 0) {\n'
                span_id: 1445
              ) (Token id:Id.Lit_Chars val:'\t\t\tlatency = sprintf("%.2f",\n' span_id:1446) 
              (Token
                id: Id.Lit_Chars
                val: '\t\t\t    1000 * (time - starts[dev, loc]))\n'
                span_id: 1447
              ) (Token id:Id.Lit_Chars val:'\t\t\tcomm = comms[dev, loc]\n' span_id:1448) 
              (Token id:Id.Lit_Chars val:'\t\t\tpid = pids[dev, loc]\n' span_id:1449) (Token id:Id.Lit_Chars val:'\n' span_id:1450) 
              (Token id:Id.Lit_Chars val:'\t\t\tif (opt_start)\n' span_id:1451) (Token id:Id.Lit_Chars val:'\t\t\t\tprintf "%-15s ", starts[dev, loc]\n' span_id:1452) 
              (Token id:Id.Lit_Chars val:'\t\t\tif (opt_end)\n' span_id:1453) (Token id:Id.Lit_Chars val:'\t\t\t\tprintf "%-15s ", time\n' span_id:1454) 
              (Token
                id: Id.Lit_Chars
                val: '\t\t\tprintf "%-12.12s %-6s %-4s %-8s %-12s %-6s %8s\\n",\n'
                span_id: 1455
              ) (Token id:Id.Lit_Chars val:'\t\t\t    comm, pid, dir, dev, loc, nsec * 512, latency\n' span_id:1456) 
              (Token id:Id.Lit_Chars val:'\t\t\tif (!opt_duration)\n' span_id:1457) (Token id:Id.Lit_Chars val:'\t\t\t\tfflush()\n' span_id:1458) 
              (Token id:Id.Lit_Chars val:'\n' span_id:1459) (Token id:Id.Lit_Chars val:'\t\t\tdelete starts[dev, loc]\n' span_id:1460) 
              (Token id:Id.Lit_Chars val:'\t\t\tdelete comms[dev, loc]\n' span_id:1461) (Token id:Id.Lit_Chars val:'\t\t\tdelete pids[dev, loc]\n' span_id:1462) 
              (Token id:Id.Lit_Chars val:'\t\t}\n' span_id:1463) (Token id:Id.Lit_Chars val:'\t\tnext\n' span_id:1464) (Token id:Id.Lit_Chars val:'\t}\n' span_id:1465) 
              (Token id:Id.Lit_Chars val:'\n' span_id:1466) 
              (Token
                id: Id.Lit_Chars
                val: '\t$0 ~ /LOST.*EVENTS/ { print "WARNING: " $0 > "/dev/stderr" }\n'
                span_id: 1467
              )
            )
          }
        )
      ]
      negated: F
    )
    (C {(end)})
  ]
)