Method constructor

packages/db-ivm/src/operators/distinct.ts:22–31

(
    id: number,
    input: DifferenceStreamReader<T>,
    output: DifferenceStreamWriter<KeyValue<number, GetValue<T>>>,
    by: (value: T) => any = (value: T) => value,
  )

  #values: Map<Hash, Multiplicity> // keeps track of the number of times each value has been seen

  constructor(
    id: number,
    input: DifferenceStreamReader<T>,
    output: DifferenceStreamWriter<KeyValue<number, GetValue<T>>>,
    by: (value: T) => any = (value: T) => value,
  ) {
    super(id, input, output)
    this.#by = by
    this.#values = new Map()
  }

  run(): void {
    const updatedValues = new Map<Hash, [Multiplicity, T]>()