def start_with(self, x):
        """Returns all arguments beginning with given string
           (or list thereof).
        """

        _args = []

        for arg in self.all:
            if _is_collection(x):
                for _x in x:
                    if arg.startswith(x):
                        _args.append(arg)
                        break
            else:
                if arg.startswith(x):
                    _args.append(arg)

        return ArgsList(_args, no_argv=True)
Returns all arguments beginning with given string
           (or list thereof).