(command.CommandList
  children: [
    (command.ShAssignment
      pairs: [
        (assign_pair
          lhs: (sh_lhs_expr.Name name:test_description)
          op: assign_op.Equal
          rhs: {(SQ (Token id:Id.Lit_Chars val:'histogram diff algorithm' span_id:6))}
          spids: [4]
        )
      ]
    )
    (C {(.)} {(./test-lib.sh)})
    (C {(.)} {(DQ ($ Id.VSub_DollarName '$TEST_DIRECTORY')) (/lib-diff-alternative.sh)})
    (C {(test_diff_frobnitz)} {(DQ (histogram))})
    (C {(test_diff_unique)} {(DQ (histogram))})
    (C {(test_done)})
  ]
)