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
  =====================  ===============================================
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docstr: Change the composition mode of the item. This is useful when overlaying
  multiple items.
  
  Parameters
  ----------
  mode : ``QtGui.QPainter.CompositionMode``
      Composition of the item, often used when overlaying items.  Common
      options include:
  
      ``QPainter.CompositionMode.CompositionMode_SourceOver`` (Default)
      Image replaces the background if it is opaque. Otherwise, it uses
      the alpha channel to blend the image with the background.
  
      ``QPainter.CompositionMode.CompositionMode_Overlay`` Image color is
      mixed with the background color to reflect the lightness or
      darkness of the background
  
      ``QPainter.CompositionMode.CompositionMode_Plus`` Both the alpha
      and color of the image and background pixels are added together.
  
      ``QPainter.CompositionMode.CompositionMode_Plus`` The output is the
      image color multiplied by the background.
  
      See ``QPainter::CompositionMode`` in the Qt Documentation for more
      options and details
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code: def setCompositionMode(self, mode):
      """
      Change the composition mode of the item. This is useful when overlaying
      multiple items.
  
      Parameters
      ----------
      mode : ``QtGui.QPainter.CompositionMode``
          Composition of the item, often used when overlaying items.  Common
          options include:
  
          ``QPainter.CompositionMode.CompositionMode_SourceOver`` (Default)
          Image replaces the background if it is opaque. Otherwise, it uses
          the alpha channel to blend the image with the background.
  
          ``QPainter.CompositionMode.CompositionMode_Overlay`` Image color is
          mixed with the background color to reflect the lightness or
          darkness of the background
  
          ``QPainter.CompositionMode.CompositionMode_Plus`` Both the alpha
          and color of the image and background pixels are added together.
  
          ``QPainter.CompositionMode.CompositionMode_Plus`` The output is the
          image color multiplied by the background.
  
          See ``QPainter::CompositionMode`` in the Qt Documentation for more
          options and details
      """
      self.opts["compositionMode"] = mode
      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 5 for calling the PlotCurveItem obj's underlying member method code with example usage: obj.setCompositionMode(mode) without return types