Convert `\r\r\n`,`\r\n`, `\n\r` to `\n.`

        :param a_string: A string that may have non-normalized line feeds
            i.e. output returned from device, or a device prompt
        :type a_string: str

def normalize_linefeeds(self, a_string):
        """Convert `\r\r\n`,`\r\n`, `\n\r` to `\n.`

        :param a_string: A string that may have non-normalized line feeds
            i.e. output returned from device, or a device prompt
        :type a_string: str
        """
        newline = re.compile("(\r\r\r\n|\r\r\n|\r\n|\n\r)")
        a_string = newline.sub(self.RESPONSE_RETURN, a_string)
        if self.RESPONSE_RETURN == "\n":
            # Convert any remaining \r to \n
            return re.sub("\r", self.RESPONSE_RETURN, a_string)