code: def getCharStringForGlyph(self, glyph, private, globalSubrs):
          
          width = glyph.width
          defaultWidth = private.defaultWidthX
          nominalWidth = private.nominalWidthX
          if width == defaultWidth:
              # if width equals the default it can be omitted from charstring
              width = None
          else:
              # subtract the nominal width
              width -= nominalWidth
          if width is not None:
              width = otRound(width)
          pen = T2CharStringPen(width, self.allGlyphs,
                                roundTolerance=self.roundTolerance)
          glyph.draw(pen)
          charString = pen.getCharString(
              private, globalSubrs, optimize=self.optimizeCFF
          )
          return charString
docs: Get a Type2CharString for the *glyph*
  
          **This should not be called externally.** Subclasses
          may override this method to handle the charstring creation
          in a different way if desired.