class_docstr: Class representing a single plot curve. Instances of this class are created
  automatically as part of :class:`PlotDataItem <pyqtgraph.PlotDataItem>`; 
  these rarely need to be instantiated directly.
  
  Features:
  
    - Fast data update
    - Fill under curve
    - Mouse interaction
  
  =====================  ===============================================
  **Signals:**
  sigPlotChanged(self)   Emitted when the data being plotted has changed
  sigClicked(self, ev)   Emitted when the curve is clicked
  =====================  ===============================================
class_docstr_tok: ["Class","representing","a","single","plot","curve",".","Instances","of","this","class","are","created","automatically","as","part","of",":","class",":","`","PlotDataItem","<","pyqtgraph.PlotDataItem",">","`",";","these","rarely","need","to","be","instantiated","directly",".","Features",":","-","Fast","data","update","-","Fill","under","curve","-","Mouse","interaction","=====================","===============================================","*","*","Signals",":","*","*","sigPlotChanged","(","self",")","Emitted","when","the","data","being","plotted","has","changed","sigClicked","(","self",",","ev",")","Emitted","when","the","curve","is","clicked","=====================","==============================================="]
docstr: Set the shadow pen used to draw behind the primary pen.
  This pen must have a larger width than the primary
  pen to be visible. Arguments are passed to 
  :func:`mkPen <pyqtgraph.mkPen>`
docstr_tok: ["Set","the","shadow","pen","used","to","draw","behind","the","primary","pen",".","This","pen","must","have","a","larger","width","than","the","primary","pen","to","be","visible",".","Arguments","are","passed","to",":","func",":","`","mkPen","<","pyqtgraph.mkPen",">","`"]
code: def setShadowPen(self, *args, **kargs):
      """
      Set the shadow pen used to draw behind the primary pen.
      This pen must have a larger width than the primary
      pen to be visible. Arguments are passed to
      :func:`mkPen <pyqtgraph.mkPen>`
      """
      if args and args[0] is None:
          self.opts["shadowPen"] = None
      else:
          self.opts["shadowPen"] = fn.mkPen(*args, **kargs)
      self.invalidateBounds()
      self.update()
  
imports: from ..Qt import QtCore, QtGui, QtWidgets
  import math
  import sys
  import warnings
  import numpy
  from ..None import Qt, debug
  from ..None import functions
  from ..None import getConfigOption
  from .GraphicsObject import GraphicsObject
label_desc: Use image node_id 13 for calling the PlotCurveItem obj's underlying member method code with example usage: obj.setShadowPen() without return types