ResultSet
result variable: x
result variable: y
result variable: a
size: 2
solution: ResultSolution
  binding: ResultBinding
    variable: x
  binding: ResultBinding
    variable: y
    value: http://rdf.hp.com/p
  binding: ResultBinding
    variable: a
    value: http://rdf.hp.com/p
solution: ResultSolution
  binding: ResultBinding
    variable: x
    value: http://rdf.hp.com/p
  binding: ResultBinding
    variable: y
    value: http://rdf.hp.com/p
  binding: ResultBinding
    variable: a
    value: http://rdf.hp.com/p