ResultSet
result variable: x
size: 4
solution: ResultSolution
  binding: ResultBinding
    variable: x
    value: r-2
solution: ResultSolution
  binding: ResultBinding
    variable: x
    value: r-1
solution: ResultSolution
  binding: ResultBinding
    variable: x
    value: r-1
solution: ResultSolution
  binding: ResultBinding
    variable: x
    value: r-2