query A($atOtherHomes: Boolean) {
  ...HouseTrainedFragment
}

query B($atOtherHomes: Boolean) {
  ...HouseTrainedFragment
}

fragment HouseTrainedFragment on Query {
  dog {
    isHouseTrained(atOtherHomes: $atOtherHomes)
  }
}

type Query {
  dog: Dog
}

type Dog {
  name: String!
  nickname: String
  barkVolume: Int
  isHouseTrained(atOtherHomes: Boolean): Boolean!
}