(command.CommandList
  children: [
    (command.ShAssignment
      left: <Id.Lit_VarLike 'nm='>
      pairs: [
        (AssignPair
          left: <Id.Lit_VarLike 'nm='>
          lhs: (sh_lhs_expr.Name left:<Id.Lit_VarLike 'nm='> name:nm)
          op: assign_op.Equal
          rhs: {(DQ ($ Id.VSub_Number 1))}
        )
      ]
      redirects: []
    )
    (command.ShAssignment
      left: <Id.Lit_VarLike 'file='>
      pairs: [
        (AssignPair
          left: <Id.Lit_VarLike 'file='>
          lhs: (sh_lhs_expr.Name left:<Id.Lit_VarLike 'file='> name:file)
          op: assign_op.Equal
          rhs: {(DQ ($ Id.VSub_Number 2))}
        )
      ]
      redirects: []
    )
    (command.Pipeline
      children: [
        (command.Simple
          blame_tok: <Id.VSub_DollarName '$nm'>
          more_env: []
          words: [{($ Id.VSub_DollarName nm)} {(DQ ($ Id.VSub_DollarName file))}]
          redirects: []
          do_fork: T
        )
        (command.Simple
          blame_tok: <grep>
          more_env: []
          words: [{<grep>} {(SQ <'^ *U'>)}]
          redirects: [
            (Redir op:<Id.Redir_Great '>'> loc:(redir_loc.Fd fd:1) arg:{<'/dev/null'>})
            (Redir op:<Id.Redir_GreatAnd '2>&'> loc:(redir_loc.Fd fd:2) arg:{<1>})
          ]
          do_fork: T
        )
      ]
      ops: [<Id.Op_Pipe _>]
    )
    (command.If
      if_kw: <Id.KW_If if>
      arms: [
        (IfArm
          keyword: <Id.KW_If if>
          cond: 
            (condition.Shell
              commands: [
                (command.Sentence
                  child: 
                    (command.Simple
                      blame_tok: <Id.Lit_LBracket '['>
                      more_env: []
                      words: [
                        {<Id.Lit_LBracket '['>}
                        {($ Id.VSub_QMark '?')}
                        {<-eq>}
                        {<1>}
                        {<Id.Lit_RBracket ']'>}
                      ]
                      redirects: []
                      do_fork: T
                    )
                  terminator: <Id.Op_Semi _>
                )
              ]
            )
          then_kw: <Id.KW_Then then>
          action: [(command.ControlFlow keyword:<Id.ControlFlow_Exit exit> arg_word:{<0>})]
          spids: [34 47]
        )
      ]
      else_kw: <Id.KW_Else else>
      else_action: [
        (command.Simple
          blame_tok: <echo>
          more_env: []
          words: [{<echo>} {(DQ ($ Id.VSub_DollarName file) <': undefined symbols found'>)}]
          redirects: [(Redir op:<Id.Redir_GreatAnd '>&'> loc:(redir_loc.Fd fd:1) arg:{<2>})]
          do_fork: T
        )
        (command.ControlFlow keyword:<Id.ControlFlow_Exit exit> arg_word:{<1>})
      ]
      fi_kw: <Id.KW_Fi fi>
      redirects: []
    )
  ]
)