Attempt to become root.

def enable(self, cmd="sudo su", pattern="ssword", re_flags=re.IGNORECASE):
        """Attempt to become root."""
        delay_factor = self.select_delay_factor(delay_factor=0)
        output = ""
        if not self.check_enable_mode():
            self.write_channel(self.normalize_cmd(cmd))
            time.sleep(0.3 * delay_factor)
            try:
                output += self.read_channel()
                if re.search(pattern, output, flags=re_flags):
                    self.write_channel(self.normalize_cmd(self.secret))
                self.set_base_prompt()
            except socket.timeout:
                raise NetMikoTimeoutException(
                    "Timed-out reading channel, data not available."
                )
            if not self.check_enable_mode():
                msg = (
                    "Failed to enter enable mode. Please ensure you pass "
                    "the 'secret' argument to ConnectHandler."
                )
                raise ValueError(msg)
        return output