docs: def _ensure_ifaces_tuple(ifaces):
      """Convert to a tuple of interfaces and raise if not interfaces."""
      try:
  
          ifaces = tuple(ifaces)
  
      except TypeError:
  
          ifaces = (ifaces,)
  
      for iface in ifaces:
  
          if not _issubclass(iface, ibc.Iface):
  
              raise TypeError('Can only compare against interfaces.')
  
      return ifaces