def _get_layer_min_max(self, oid_field_name):
query_args = self._build_query_args({<EOL>'<STR_LIT:f>': '<STR_LIT>',<EOL>'<STR_LIT>': '<STR_LIT>',<EOL>'<STR_LIT>': json.dumps([<EOL>dict(statisticType='<STR_LIT>', onStatisticField=oid_field_name, outStatisticFieldName='<STR_LIT>'),<EOL>dict(statisticType='<STR_LIT>', onStatisticField=oid_field_name, outStatisticFieldName='<STR_LIT>'),<EOL>], separators=('<STR_LIT:U+002C>', '<STR_LIT::>'))<EOL>})<EOL>headers = self._build_headers()<EOL>url = self._build_url('<STR_LIT>')<EOL>response = self._request('<STR_LIT:GET>', url, params=query_args, headers=headers)<EOL>metadata = self._handle_esri_errors(response, "<STR_LIT>")<EOL>min_max_values = metadata['<STR_LIT>'][<NUM_LIT:0>]['<STR_LIT>'].values()<EOL>min_value = min(min_max_values)<EOL>max_value = max(min_max_values)<EOL>query_args = self._build_query_args({<EOL>'<STR_LIT:f>': '<STR_LIT>',<EOL>'<STR_LIT>': '<STR_LIT:*>',<EOL>'<STR_LIT>': json.dumps([<EOL>dict(statisticType='<STR_LIT>', onStatisticField=oid_field_name, outStatisticFieldName='<STR_LIT>'),<EOL>dict(statisticType='<STR_LIT>', onStatisticField=oid_field_name, outStatisticFieldName='<STR_LIT>'),<EOL>], separators=('<STR_LIT:U+002C>', '<STR_LIT::>'))<EOL>})<EOL>query_args = self._build_query_args({<EOL>'<STR_LIT>': '<STR_LIT>'.format(<EOL>oid_field_name,<EOL>min_value,<EOL>oid_field_name,<EOL>max_value<EOL>),<EOL>'<STR_LIT>': '<STR_LIT:true>',<EOL>'<STR_LIT:f>': '<STR_LIT>',<EOL>})<EOL>headers = self._build_headers()<EOL>url = self._build_url('<STR_LIT>')<EOL>response = self._request('<STR_LIT:GET>', url, params=query_args, headers=headers)<EOL>oid_data = self._handle_esri_errors(response, "<STR_LIT>")<EOL>if not oid_data or not oid_data.get('<STR_LIT>') or min_value not in oid_data['<STR_LIT>'] or max_value not in oid_data['<STR_LIT>']:<EOL><INDENT>raise EsriDownloadError('<STR_LIT>')<EOL><DEDENT>return (min_value, max_value)<EOL>
Find the min and max values for the OID field.