def add_field(self, name, fragment_size=150, number_of_fragments=3, fragment_offset=None, order="score", type=None):
        """
        Add a field to Highlinghter
        """
        data = {}
        if fragment_size:
            data['fragment_size'] = fragment_size
        if number_of_fragments is not None:
            data['number_of_fragments'] = number_of_fragments
        if fragment_offset is not None:
            data['fragment_offset'] = fragment_offset
        if type is not None:
            data['type'] = type
        data['order'] = order
        self.fields[name] = data
Add a field to Highlinghter