code: def set_font_increment(self, value):
          
  
          font = self.font()
          point_size = font.pointSize() + value
          if point_size < self.__minimum_font_point_size or point_size > self.__maximum_font_point_size:
              return False
  
          font.setPointSize(point_size)
          self.setFont(font)
          return True
docs: Increments the document font size.
  
          :param value: Font size increment.
          :type value: int
          :return: Method success.
          :rtype: bool