code: func (c *Input) SynthesizePinchGesture(x float64, y float64, scaleFactor float64, relativeSpeed int, gestureSourceType string) (*gcdmessage.ChromeResponse, error) {
  	var v InputSynthesizePinchGestureParams
  	v.X = x
  	v.Y = y
  	v.ScaleFactor = scaleFactor
  	v.RelativeSpeed = relativeSpeed
  	v.GestureSourceType = gestureSourceType
  	return c.SynthesizePinchGestureWithParams(&v)
  }
docs: // SynthesizePinchGesture - Synthesizes a pinch gesture over a time period by issuing appropriate touch events.
  // x - X coordinate of the start of the gesture in CSS pixels.
  // y - Y coordinate of the start of the gesture in CSS pixels.
  // scaleFactor - Relative scale factor after zooming (>1.0 zooms in, <1.0 zooms out).
  // relativeSpeed - Relative pointer speed in pixels per second (default: 800).
  // gestureSourceType - Which type of input events to be generated (default: 'default', which queries the platform for the preferred input type). enum values: default, touch, mouse