parameters: (self, html, preview)
return_statement: return html
docstring: Prepare the email body before sending. Add the text preview at the
          beginning of the mail. The preview text is displayed bellow the mail
          subject of most mail client (gmail, outlook...).
  
          :param html: html content for which we want to prepend a preview
          :param preview: the preview to add before the html content
          :return: html with preprended preview
docstring_summary: Prepare the email body before sending. Add the text preview at the
          beginning of the mail. The preview text is displayed bellow the mail
          subject of most mail client (gmail, outlook...).
docstring_tokens: Prepare the email body before sending . Add the text preview at the beginning of the mail . The preview text is displayed bellow the mail subject of most mail client ( gmail outlook ... ) .
function: def _prepend_preview(self, html, preview):
          """ Prepare the email body before sending. Add the text preview at the
          beginning of the mail. The preview text is displayed bellow the mail
          subject of most mail client (gmail, outlook...).
  
          :param html: html content for which we want to prepend a preview
          :param preview: the preview to add before the html content
          :return: html with preprended preview
          """
          if preview:
              preview = preview.strip()
  
          preview_markup = convert_inline_template_to_qweb(preview)
  
          if preview:
              html_preview = Markup("""
                  <div style="display:none;font-size:1px;height:0px;width:0px;opacity:0;">
                      {}
                  </div>
              """).format(preview_markup)
              return tools.prepend_html_content(html, html_preview)
          return html
function_tokens: def _prepend_preview ( self , html , preview ) : if preview : preview = preview . strip ( ) preview_markup = convert_inline_template_to_qweb ( preview ) if preview : html_preview = Markup ( """
                  <div style="display:none;font-size:1px;height:0px;width:0px;opacity:0;">
                      {}
                  </div>
              """ ) . format ( preview_markup ) return tools . prepend_html_content ( html , html_preview ) return html