function definition$1(type) {
    const t = transform$2(type);
    return t && t.Definition || null;
  }
Process incoming pulses.
Subclasses should override this method to implement transforms.
@param {Parameters} _ - The operator parameter values.
@param {Pulse} pulse - The current dataflow pulse.
@return {Pulse} The output pulse (or StopPropagation). A falsy return
  value (including undefined) will let the input pulse pass through.