docs: def _get_prefixes(self):
          """Get the possible nick prefixes and associated modes for a client."""
          prefixes = {
              "@": "o",
              "+": "v",
          }
          feature_prefixes = self.server.features.get('PREFIX')
          if feature_prefixes:
              modes = feature_prefixes[1:len(feature_prefixes)//2]
              symbols = feature_prefixes[len(feature_prefixes)//2+1:]
              prefixes = dict(zip(symbols, modes))
          return prefixes