code: def convert_inline_formula_elements(self):
          
          for inline in self.main.getroot().findall('.//inline-formula'):
              #inline-formula elements will be modified in situ
              remove_all_attributes(inline)
              inline.tag = 'span'
              inline.attrib['class'] = 'inline-formula'
              inline_graphic = inline.find('inline-graphic')
              if inline_graphic is None:
                  # Do nothing more if there is no graphic
                  continue
              #Need to conver the inline-graphic element to an img element
              inline_graphic.tag = 'img'
              #Get a copy of the attributes, then remove them
              inline_graphic_attributes = copy(inline_graphic.attrib)
              remove_all_attributes(inline_graphic)
              #Create a file reference for the image
              xlink_href = ns_format(inline_graphic, 'xlink:href')
              graphic_xlink_href = inline_graphic_attributes[xlink_href]
              file_name = graphic_xlink_href.split('.')[-1] + '.png'
              img_dir = 'images-' + self.doi_suffix()
              img_path = '/'.join([img_dir, file_name])
              #Set the source to the image path
              inline_graphic.attrib['src'] = img_path
              inline_graphic.attrib['class'] = 'inline-formula'
              inline_graphic.attrib['alt'] = 'An Inline Formula'
docs: <inline-formula> elements must be converted to be conforming
  
          These elements may contain <inline-graphic> elements, textual content,
          or both.