Copy-pasted from upstream class until
        https://github.com/rtfd/CommonMark-py/pull/90 is merged

def image(self, node, entering):
        '''
        Copy-pasted from upstream class until
        https://github.com/rtfd/CommonMark-py/pull/90 is merged
        '''
        if entering:
            if self.disable_tags == 0:
                if self.options.get('safe') and \
                   potentially_unsafe(node.destination):
                    self.lit('<img src="" alt="')
                else:
                    self.lit('<img src="' +
                             self.escape(node.destination, True) +
                             '" alt="')
            self.disable_tags += 1
        else:
            self.disable_tags -= 1
            if self.disable_tags == 0:
                if node.title:
                    self.lit('" title="' + self.escape(node.title, True))
                self.lit('" />')