class_docstr: Filter used to color visuals by a picking ID.
  
  Note that the ID color uses the alpha channel, so this may not be used
  with blending enabled.
code: def id(self, id):
      if id < 1:
          raise ValueError("Picking ID must be integer > 0.")
      id_color = struct.unpack("<4B", struct.pack("<I", id))
      self.fshader["id_color"] = [x / 255.0 for x in id_color]
      self._id = id
      self._id_color = id_color
  
file_path: vispy/vispy/visuals/filters/picking.py
imports: import struct
  from .base_filter import Filter
label_desc: Use image node_id 3 for calling the PickingFilter obj's underlying member method code with example usage: obj.id(id) without return types