(command.CommandList
  children: [
    (C {<set>} {<-e>})
    (command.ShFunction
      name: check
      body: 
        (BraceGroup
          children: [
            (command.ShAssignment
              pairs: [
                (assign_pair
                  lhs: (sh_lhs_expr.Name name:number_of_occurrence)
                  op: assign_op.Equal
                  rhs: 
                    {
                      (command_sub
                        left_token: <Id.Left_Backtick '`'>
                        child: 
                          (command.Pipeline
                            children: [
                              (C {<grep>} {($ Id.VSub_Number '$2')} {<'./'> ($ Id.VSub_Number '$1')} 
                                {<-o>}
                              )
                              (C {<wc>} {<-l>})
                            ]
                            negated: F
                          )
                      )
                    }
                  spids: [77]
                )
              ]
            )
            (command.If
              arms: [
                (if_arm
                  cond: 
                    (condition.Shell
                      commands: [
                        (C {<Id.Lit_LBracket '['>} {($ Id.VSub_DollarName '$number_of_occurrence')} 
                          {<Id.KW_Bang '!'> <Id.Lit_Equals '='>} {($ Id.VSub_Number '$3')} {<Id.Lit_RBracket ']'>}
                        )
                      ]
                    )
                  action: [
                    (C {<echo>} {(DQ <'String literals were not merged'>)})
                    (command.ControlFlow
                      token: <Id.ControlFlow_Exit exit>
                      arg_word: {<1>}
                    )
                  ]
                  spids: [97 111]
                )
              ]
            )
          ]
        )
    )
    (C {<check>} {<merge_string_literals.stdout>} {(DQ <abcd>)} {<2>})
  ]
)