docs: def is_alive(self):
          """Returns a boolean flag with the state of the connection."""
          null = chr(0)
          if self.remote_conn is None:
              log.error("Connection is not initialised, is_alive returns False")
              return False
          if self.protocol == "telnet":
              try:
                  # Try sending IAC + NOP (IAC is telnet way of sending command)
                  # IAC = Interpret as Command; it comes before the NOP.
                  log.debug("Sending IAC + NOP")
                  # Need to send multiple times to test connection
                  self.remote_conn.sock.sendall(telnetlib.IAC + telnetlib.NOP)
                  self.remote_conn.sock.sendall(telnetlib.IAC + telnetlib.NOP)
                  self.remote_conn.sock.sendall(telnetlib.IAC + telnetlib.NOP)
                  return True
              except AttributeError:
                  return False
          else:
              # SSH
              try:
                  # Try sending ASCII null byte to maintain the connection alive
                  log.debug("Sending the NULL byte")
                  self.write_channel(null)
                  return self.remote_conn.transport.is_active()
              except (socket.error, EOFError):
                  log.error("Unable to send", exc_info=True)
                  # If unable to send, we can tell for sure that the connection is unusable
                  return False
          return False