code: def on_mouse_press(event):
      global selected, fig
      if event.handled or event.button != 1:
          return
      if selected is not None:
          selected.set_data(width=1)
      selected = None
      for v in fig.visuals_at(event.pos):
          if isinstance(v, vp.LinePlot):
              selected = v
              break
      if selected is not None:
          selected.set_data(width=3)
          update_cursor(event.pos)
  
imports: import numpy
  import vispy.plot
  from vispy.color import get_colormap
  from vispy.io import load_data_file
label_desc: Use image node_id 1 for calling a global function with example usage: on_mouse_press(event) without return types