(self, *args, **kw)
Execute this event, but only if it has not been
        executed already for this collection.
Execute this event, but only if it has not been
        executed already for this collection.
Execute this event but only if it has not been executed already for this collection .
def exec_once(self, *args, **kw):
        """Execute this event, but only if it has not been
        executed already for this collection."""

        if not self._exec_once:
            self._exec_once_impl(False, *args, **kw)
def exec_once ( self , * args , * * kw ) : if not self . _exec_once : self . _exec_once_impl ( False , * args , * * kw )