(command.CommandList
  children: [
    (command.CommandList
      children: [
        (command.Sentence
          child: 
            (command.ShAssignment
              left: <Id.Lit_VarLike 'SRCDIR='>
              pairs: [
                (AssignPair
                  left: <Id.Lit_VarLike 'SRCDIR='>
                  lhs: (sh_lhs_expr.Name left:<Id.Lit_VarLike 'SRCDIR='> name:SRCDIR)
                  op: assign_op.Equal
                  rhs: 
                    {
                      (DQ 
                        (CommandSub
                          left_token: <Id.Left_DollarParen '$('>
                          child: 
                            (command.Simple
                              blame_tok: <dirname>
                              more_env: []
                              words: [{<dirname>} {(DQ (${ Id.VSub_Number 0))}]
                              redirects: []
                              do_fork: T
                            )
                          right: <Id.Eof_RParen _>
                        )
                      )
                    }
                )
              ]
              redirects: []
            )
          terminator: <Id.Op_Semi _>
        )
        (command.Simple
          blame_tok: <export>
          more_env: []
          words: [{<export>} {<SRCDIR>}]
          redirects: []
          do_fork: T
        )
      ]
    )
    (command.Pipeline
      children: [
        (command.Simple
          blame_tok: <m4>
          more_env: []
          words: [
            {<m4>}
            {(DQ (${ Id.VSub_Name SRCDIR) <'/../regress.m4'>)}
            {(DQ (${ Id.VSub_Name SRCDIR) <'/regress.sh'>)}
          ]
          redirects: []
          do_fork: T
        )
        (command.Simple blame_tok:<sh> more_env:[] words:[{<sh>}] redirects:[] do_fork:T)
      ]
      ops: [<Id.Op_Pipe _>]
    )
  ]
)