code: async def on_isupport_prefix(self, value):
          
          if not value:
              # No prefixes support.
              self._nickname_prefixes = collections.OrderedDict()
              return
  
          modes, prefixes = value.lstrip('(').split(')', 1)
  
          # Update valid channel modes and their behaviour as CHANMODES doesn't include PREFIX modes.
          self._channel_modes.update(set(modes))
          if not rfc1459.protocol.BEHAVIOUR_PARAMETER in self._channel_modes_behaviour:
              self._channel_modes_behaviour[rfc1459.protocol.BEHAVIOUR_PARAMETER] = set()
          self._channel_modes_behaviour[rfc1459.protocol.BEHAVIOUR_PARAMETER].update(set(modes))
  
          self._nickname_prefixes = collections.OrderedDict()
          for mode, prefix in zip(modes, prefixes):
              self._nickname_prefixes[prefix] = mode
docs: Nickname prefixes on channels and their associated modes.