def add_single(self, hostname, ports, nickname=None, **kws):
nickname = nickname or hostname<EOL>self[hostname.lower()] = ServerInfo(nickname, hostname, ports, **kws)<EOL>
Explicitly add a single entry.
Hostname is a FQDN and ports is either a single int (assumed to be TCP port)
or Electrum protocol/port number specification with spaces in between.