def _convert_strls(self, data):
convert_cols = [<EOL>col for i, col in enumerate(data)<EOL>if self.typlist[i] == <NUM_LIT> or col in self._convert_strl]<EOL>if convert_cols:<EOL><INDENT>ssw = StataStrLWriter(data, convert_cols)<EOL>tab, new_data = ssw.generate_table()<EOL>data = new_data<EOL>self._strl_blob = ssw.generate_blob(tab)<EOL><DEDENT>return data<EOL>
Convert columns to StrLs if either very large or in the
        convert_strl variable