def extract_protocol(self):
if self.present.mcs:<EOL><INDENT>return '<STR_LIT>'<EOL><DEDENT>if self.present.vht:<EOL><INDENT>return '<STR_LIT>'<EOL><DEDENT>if self.present.channel and hasattr(self, '<STR_LIT>'):<EOL><INDENT>if self.chan.five_g:<EOL><INDENT>if self.chan.ofdm:<EOL><INDENT>return '<STR_LIT>'<EOL><DEDENT><DEDENT>elif self.chan.two_g:<EOL><INDENT>if self.chan.cck:<EOL><INDENT>return '<STR_LIT>'<EOL><DEDENT>elif self.chan.ofdm or self.chan.dynamic:<EOL><INDENT>return '<STR_LIT>'<EOL><DEDENT><DEDENT><DEDENT>return '<STR_LIT:None>'<EOL>
extract 802.11 protocol from radiotap.channel.flags
        :return: str
            protocol name
            one of below in success
            [.11a, .11b, .11g, .11n, .11ac]
            None in fail