def do_enable(self, arg):
        """enable bpnumber [bpnumber ...]
        Enables the breakpoints given as a space separated list of
        breakpoint numbers.
        """
        args = arg.split()
        for i in args:
            try:
                bp = self.get_bpbynumber(i)
            except ValueError as err:
                self.error(err)
            else:
                bp.enable()
                self.done_breakpoint_state(bp, True)