'(typ, [data]) = xatom(name, arg, ...)
Allow simple extension commands notified by server in CAPABILITY response.
Assumes extension command \'name\' is legal in current state.
Returns response appropriate to extension command \'name\'.'

def xatom(self, name, *args, **kw):

    name = name.upper()
    if (not (name in Commands)):
        Commands[name] = ((self.state,), False)
    try:
        return self._simple_command(name, *args, **kw)
    finally:
        self._release_state_change()
