code: func adjustDatumKind(vals1, vals2 []types.Datum) {
  	if len(vals1) != len(vals2) {
  		return
  	}
  
  	for i, val1 := range vals1 {
  		val2 := vals2[i]
  		if val1.Kind() != val2.Kind() {
  			if (val1.Kind() == types.KindBytes || val1.Kind() == types.KindString) &&
  				(val2.Kind() == types.KindBytes || val2.Kind() == types.KindString) {
  				vals1[i].SetBytes(val1.GetBytes())
  				vals2[i].SetBytes(val2.GetBytes())
  			}
  		}
  	}
  }
docs: // adjustDatumKind treats KindString as KindBytes.