code: def on_move(self, event):
      if (
          self.pressevent is None
          or event.inaxes != self.pressevent.inaxes
      ):
          return
  
      dx = event.xdata - self.pressevent.xdata
      dy = event.ydata - self.pressevent.ydata
      circ.center = self.x0 + dx, self.y0 + dy
      line.set_clip_path(circ)
      fig.canvas.draw()
  
file_path: matplotlib/galleries/examples/event_handling/looking_glass.py
imports: import matplotlib.pyplot
  import numpy
  import matplotlib.patches
label_desc: Use image node_id 4 for calling the EventHandler obj's underlying member method code with example usage: obj.on_move(event) without return types