code: def vis_image(img, ax=None):
      """Visualize a color image.
  
      Args:
          img (~numpy.ndarray): See the table below.
              If this is :obj:`None`, no image is displayed.
          ax (matplotlib.axes.Axis): The visualization is displayed on this
              axis. If this is :obj:`None` (default), a new axis is created.
  
      .. csv-table::
          :header: name, shape, dtype, format
  
          :obj:`img`, ":math:`(3, H, W)`", :obj:`float32`, \
          "RGB, :math:`[0, 255]`"
  
      Returns:
          ~matploblib.axes.Axes:
          Returns the Axes object with the plot for further tweaking.
  
      """
      from matplotlib import pyplot as plot
  
      if ax is None:
          fig = plot.figure()
          ax = fig.add_subplot(1, 1, 1)
      if img is not None:
          # CHW -> HWC
          img = img.transpose((1, 2, 0))
          ax.imshow(img.astype(np.uint8))
      return ax
  
label_desc: Use image node_id 1 for calling a global function with example usage: vis_image(img, ax) and returns: ax