def lexically_searchable_fields_names(self) -> Set[str]:
        """Return a set of field names (str) that are lexically searchable.

        These are the original field names without any Marqo prefix. You should use this to generate
        the searchable fields in your lexical search query.

        Note that field.name is not identical to field.lexical_field_name. The latter is the name of the field
        that is used in the index schema"""
        return self._cache_or_get('lexically_searchable_fields_names',
                                  lambda: {field.name for field in self.lexical_fields}
                                  )
Return a set of field names (str) that are lexically searchable.

        These are the original field names without any Marqo prefix. You should use this to generate
        the searchable fields in your lexical search query.

        Note that field.name is not identical to field.lexical_field_name. The latter is the name of the field
        that is used in the index schema
src/marqo/core/models/marqo_index.py