@rule('<STR_LIT>')<EOL><INDENT>def visit_nb_filter(self, _, children):<DEDENT>
return self.SliceFilter(children[<NUM_LIT:0>])<EOL>
A number used as a filter, to retrieve an entry in a list.

        Arguments
        ---------
        _ (node) : parsimonious.nodes.Node.
        children : list
            - 0: a number

        Returns
        -------
        .resources.SliceFilter
            An instance of ``SliceFilter`` filed with the number as index, and no slice.

        Example
        -------

        >>> FiltersWithSlicingParserMixin('1', default_rule='NB_FILTER').data
        [1]