[1] <INTSXP[10]> (altrep )
  _class [2] <RAWSXP[144]> ()
    _attrib [3] <LISTSXP> ()
      [4] <SYMSXP: compact_intseq> ()
      [5] <SYMSXP: base> ()
      [6] <INTSXP[1]> ()
  _data1 [7] <REALSXP[3]> ()
  _data2 <NILSXP>
