docstr: Return the depth value of this item. See setDepthValue for more information.
code: def depthValue(self):
      """Return the depth value of this item. See setDepthValue for more information."""
      return self.__depthValue
  
imports: from OpenGL.GL import *
  from OpenGL import GL
  from ..None import Transform3D
  from ..Qt import QtCore
label_desc: Use image node_id 10 for calling the GLGraphicsItem obj's underlying member method code with example usage: obj.depthValue() and returns: self