class_docstr: Class that provides a series of GL functions that do not fit
  in the object oriented part of gloo. An instance of this class is
  associated with each canvas.
docstr: Control the front or back writing of individual bits in the stencil
  
  Parameters
  ----------
  mask : int
      Mask that is ANDed with ref and stored stencil value.
  face : str
      Can be 'front', 'back', or 'front_and_back'.
docstr_tok: ["Control","the","front","or","back","writing","of","individual","bits","in","the","stencil","Parameters","--","--","--","--","--","mask",":","int","Mask","that","is","ANDed","with","ref","and","stored","stencil","value",".","face",":","str","Can","be","'front","'",",","'back","'",",","or","'front_and_back","'","."]
code: def set_stencil_mask(self, mask=8, face="front_and_back"):
      """Control the front or back writing of individual bits in the stencil
  
      Parameters
      ----------
      mask : int
          Mask that is ANDed with ref and stored stencil value.
      face : str
          Can be 'front', 'back', or 'front_and_back'.
      """
      self.glir.command(
          "FUNC", "glStencilMaskSeparate", face, int(mask)
      )
  
imports: import numpy
  from copy import deepcopy
  from .None import gl
  from ..color import Color
  from ..util import logger
label_desc: Use image node_id 16 for calling the BaseGlooFunctions obj's underlying member method code with example usage: obj.set_stencil_mask(mask, face) without return types