Convert '\r\n' or '\r\r\n' to '\n, and remove extra '\r's in the text.

def normalize_linefeeds(self, a_string):
        """Convert '\r\n' or '\r\r\n' to '\n, and remove extra '\r's in the text."""
        newline = re.compile(r"(\r\r\n|\r\n)")
        # NX-OS fix for incorrect MD5 on 9K (due to strange <enter> patterns on NX-OS)
        return newline.sub(self.RESPONSE_RETURN, a_string).replace("\r", "\n")