def METHOD_NAME(self, name, filter_values):
    """
    Add a filter for a facet.
    """
    # normalize the value into a list
    if not isinstance(filter_values, (tuple, list)):
        if filter_values is None:
            return
        filter_values = [
            filter_values,
        ]
    # remember the filter values for use in FacetedResponse
    self.filter_values[name] = filter_values
    # get the filter from the facet
    f = self.facets[name].METHOD_NAME(filter_values)
    if f is None:
        return
    self._filters[name] = f