Check to see if the file exists on the device
        :return:

def md5sum(self):
        """
        Check to see if the file exists on the device
        :return:
        """
        cmd = 'show file {dir}:{bin} md5sum'.format(
            dir=self.DESTDIR, bin=self.image)

        run = self.device.api.exec_opcmd
        try:
            got = run(cmd)
            return got.get('file_content_md5sum').strip()
        except:  # NOQA
            return None