(command.CommandList
  children: [
    (command.ShAssignment
      pairs: [
        (assign_pair
          lhs: (sh_lhs_expr.Name name:test_description)
          op: assign_op.Equal
          rhs: {(SQ <'performance of filter-branch'>)}
          spids: [4]
        )
      ]
    )
    (C {<.>} {<'./perf-lib.sh'>})
    (C {<test_perf_default_repo>})
    (C {<test_checkout_worktree>})
    (C {<test_expect_success>} {(SQ <'mark bases for tests'>)} 
      {(SQ <'\n'> <'\tgit tag -f tip &&\n'> <'\tgit tag -f base HEAD~100\n'>)}
    )
    (C {<test_perf>} {(SQ <'noop filter'>)} 
      {(SQ <'\n'> <'\tgit checkout --detach tip &&\n'> <'\tgit filter-branch -f base..HEAD\n'>)}
    )
    (C {<test_done>})
  ]
)