(CommandList
  children: [
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:PS4)
          op: Equal
          rhs: 
            {
              (SQ <"-(${BASH_SOURCE}:${LINENO}): ${FUNCNAME[0]} - [${SHLVL},${BASH_SUBSHELL}, $?]\n">)
            }
          spids: [0]
        )
      ]
      spids: [0]
    )
    (C {(shopt)} {(-s)} {(extdebug)})
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:_Dbg_libdir)
          op: Equal
          rhs: {($ VSub_Name "$abs_top_srcdir")}
          spids: [12]
        )
      ]
      spids: [12]
    )
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:shunit_file)
          op: Equal
          rhs: {(${ VSub_Name abs_top_srcdir) (test/unit/shunit2)}
          spids: [15]
        )
      ]
      spids: [15]
    )
    (C {(set)} {(--)} {(SQ <-q>)})
  ]
)