(command.CommandList
  children: [
    (command.If
      arms: [
        (if_arm
          cond: 
            (condition.Shell
              commands: [
                (command.Sentence
                  child: 
                    (command.DBracket
                      expr: 
                        (bool_expr.Binary
                          op_id: Id.BoolBinary_GlobDEqual
                          left: {($ Id.VSub_Number '$0')}
                          right: 
                            {
                              (braced_var_sub
                                token: <Id.VSub_Name BASH_SOURCE>
                                bracket_op: (bracket_op.ArrayIndex expr:{<Id.Lit_Digits 0>})
                              )
                            }
                        )
                    )
                  terminator: <Id.Op_Semi _>
                )
              ]
            )
          action: [
            (command.ShAssignment
              pairs: [
                (assign_pair
                  lhs: (sh_lhs_expr.Name name:dirname)
                  op: assign_op.Equal
                  rhs: 
                    {
                      (braced_var_sub
                        token: <Id.VSub_Name BASH_SOURCE>
                        bracket_op: (bracket_op.ArrayIndex expr:{<Id.Lit_Digits 0>})
                        suffix_op: 
                          (suffix_op.Unary
                            tok: <Id.VOp1_Percent '%'>
                            arg_word: {<Id.Lit_Slash '/'> <Id.Lit_Other '*'>}
                          )
                      )
                    }
                  spids: [80]
                )
              ]
            )
            (command.AndOr
              ops: [Id.Op_DAmp Id.Op_DPipe]
              children: [
                (command.DBracket
                  expr: 
                    (bool_expr.Binary
                      op_id: Id.BoolBinary_GlobDEqual
                      left: {($ Id.VSub_DollarName '$dirname')}
                      right: {($ Id.VSub_Number '$0')}
                    )
                )
                (command.ShAssignment
                  pairs: [
                    (assign_pair
                      lhs: (sh_lhs_expr.Name name:top_dir)
                      op: assign_op.Equal
                      rhs: {(SQ <..>)}
                      spids: [104]
                    )
                  ]
                )
                (command.ShAssignment
                  pairs: [
                    (assign_pair
                      lhs: (sh_lhs_expr.Name name:top_dir)
                      op: assign_op.Equal
                      rhs: {(${ Id.VSub_Name dirname) <'/..'>}
                      spids: [111]
                    )
                  ]
                )
              ]
            )
            (command.ForEach
              iter_name: lib_file
              iter_words: [{<help>} {<alias>}]
              do_arg_iter: F
              body: 
                (command.DoGroup
                  children: [
                    (command.Sentence
                      child: 
                        (C {<source>} 
                          {($ Id.VSub_DollarName '$top_dir') <'/lib/'> (${ Id.VSub_Name lib_file) <.sh>}
                        )
                      terminator: <Id.Op_Semi _>
                    )
                  ]
                )
            )
          ]
          spids: [58 77]
        )
      ]
    )
    (C {<_Dbg_help_add>} {<down>} 
      {
        (SQ <'**down** [*count*]\n'> <'\n'> 
          <'Move the current frame down in the stack trace (to an newer frame). 0 is\n'> <'the most recent frame.\n'> <'\n'> <'If *count* is omitted, use 1.\n'> <'\n'> <'See also:\n'> 
          <'---------\n'> <'\n'> <'**down** and **frame**.'>
        )
      } {<1>} {<_Dbg_complete_down>}
    )
    (command.ShFunction
      name: _Dbg_complete_down
      body: 
        (BraceGroup
          children: [
            (command.Sentence
              child: (C {<typeset>} {<-i>} {<start>})
              terminator: <Id.Op_Semi _>
            )
            (command.DParen
              child: 
                (arith_expr.BinaryAssign
                  op_id: Id.Arith_Equal
                  left: <Id.Lit_ArithVarLike start>
                  right: 
                    (arith_expr.Binary
                      op_id: Id.Arith_Plus
                      left: 
                        (arith_expr.Binary
                          op_id: Id.Arith_Plus
                          left: 
                            (arith_expr.Unary
                              op_id: Id.Node_UnaryMinus
                              child: <Id.Lit_ArithVarLike _Dbg_stack_size>
                            )
                          right: {<Id.Lit_Digits 2>}
                        )
                      right: <Id.Lit_ArithVarLike _Dbg_stack_pos>
                    )
                )
            )
            (command.Sentence
              child: (C {<typeset>} {<-i>} {<end>})
              terminator: <Id.Op_Semi _>
            )
            (command.DParen
              child: 
                (arith_expr.BinaryAssign
                  op_id: Id.Arith_Equal
                  left: <Id.Lit_ArithVarLike end>
                  right: 
                    (arith_expr.Binary
                      op_id: Id.Arith_Minus
                      left: 
                        (arith_expr.Binary
                          op_id: Id.Arith_Minus
                          left: <Id.Lit_ArithVarLike _Dbg_stack_size>
                          right: {<Id.Lit_Digits 3>}
                        )
                      right: <Id.Lit_ArithVarLike _Dbg_stack_pos>
                    )
                )
            )
            (C {<_Dbg_complete_num_range>} {($ Id.VSub_DollarName '$start')} 
              {($ Id.VSub_DollarName '$end')}
            )
          ]
        )
    )
    (command.ShFunction
      name: _Dbg_do_down
      body: 
        (BraceGroup
          children: [
            (command.AndOr
              ops: [Id.Op_DAmp]
              children: [
                (C {<_Dbg_not_running>})
                (command.ControlFlow
                  token: <Id.ControlFlow_Return return>
                  arg_word: {<3>}
                )
              ]
            )
            (C {<typeset>} 
              {<Id.Lit_VarLike 'count='> 
                (braced_var_sub
                  token: <Id.VSub_Number 1>
                  suffix_op: (suffix_op.Unary tok:<Id.VTest_ColonHyphen ':-'> arg_word:{<1>})
                )
              }
            )
            (C {<_Dbg_is_signed_int>} {($ Id.VSub_DollarName '$count')})
            (command.If
              arms: [
                (if_arm
                  cond: 
                    (condition.Shell
                      commands: [
                        (command.Sentence
                          child: 
                            (command.DParen
                              child: 
                                (arith_expr.Binary
                                  op_id: Id.Arith_DEqual
                                  left: {<Id.Lit_Digits 0>}
                                  right: {($ Id.VSub_QMark '$?')}
                                )
                            )
                          terminator: <Id.Op_Semi _>
                        )
                      ]
                    )
                  action: [
                    (C {<_Dbg_frame_adjust>} {($ Id.VSub_DollarName '$count')} {<-1>})
                    (C {<typeset>} {<-i>} {<Id.Lit_VarLike 'rc='> ($ Id.VSub_QMark '$?')})
                  ]
                  spids: [263 278]
                )
              ]
              else_action: [
                (C {<_Dbg_errmsg>} {(DQ <'Expecting an integer; got '> ($ Id.VSub_DollarName '$count'))})
                (C {<typeset>} {<-i>} {<Id.Lit_VarLike 'rc='> <2>})
              ]
            )
            (command.AndOr
              ops: [Id.Op_DAmp]
              children: [
                (command.DParen
                  child: 
                    (arith_expr.Binary
                      op_id: Id.Arith_DEqual
                      left: {<Id.Lit_Digits 0>}
                      right: <Id.Lit_ArithVarLike rc>
                    )
                )
                (command.ShAssignment
                  pairs: [
                    (assign_pair
                      lhs: (sh_lhs_expr.Name name:_Dbg_last_cmd)
                      op: assign_op.Equal
                      rhs: {(SQ <down>)}
                      spids: [329]
                    )
                  ]
                )
              ]
            )
            (command.ControlFlow
              token: <Id.ControlFlow_Return return>
              arg_word: {($ Id.VSub_DollarName '$rc')}
            )
          ]
        )
    )
    (command.If
      arms: [
        (if_arm
          cond: 
            (condition.Shell
              commands: [
                (command.Sentence
                  child: 
                    (command.DBracket
                      expr: 
                        (bool_expr.Binary
                          op_id: Id.BoolBinary_GlobDEqual
                          left: {($ Id.VSub_Number '$0')}
                          right: 
                            {
                              (braced_var_sub
                                token: <Id.VSub_Name BASH_SOURCE>
                                bracket_op: (bracket_op.ArrayIndex expr:{<Id.Lit_Digits 0>})
                              )
                            }
                        )
                    )
                  terminator: <Id.Op_Semi _>
                )
              ]
            )
          action: [
            (command.ForEach
              iter_name: _Dbg_file
              iter_words: [{<help>} {<msg>} {<sort>} {<columnize>}]
              do_arg_iter: F
              body: 
                (command.DoGroup
                  children: [
                    (C {<source>} 
                      {(${ Id.VSub_Name top_dir) <'/lib/'> (${ Id.VSub_Name _Dbg_file) <.sh>}
                    )
                  ]
                )
            )
            (C {<source>} {(${ Id.VSub_Name top_dir) <'/command/help.sh'>})
            (command.ShAssignment
              pairs: [
                (assign_pair
                  lhs: (sh_lhs_expr.Name name:_Dbg_args)
                  op: assign_op.Equal
                  rhs: {(SQ <down>)}
                  spids: [409]
                )
              ]
            )
            (C {<_Dbg_do_help>} {<down>})
          ]
          spids: [345 364]
        )
      ]
    )
  ]
)