code: def _get_font_size(document, style):
      
  
      font_size = style.get_font_size()
  
      if  font_size == -1:
          if style.based_on:
              based_on = document.styles.get_by_id(style.based_on)
              if based_on:
                  return _get_font_size(document, based_on)
  
      return font_size
docs: Get font size defined for this style.
  
      It will try to get font size from it's parent style if it is not defined by original style. 
  
      :Args:
        - document (:class:`ooxml.doc.Document`): Document object
        - style (:class:`ooxml.doc.Style`): Style object
  
      :Returns:
        Returns font size as a number. -1 if it can not get font size.