PHP_HTTP_API zend_string *php_http_header_value_to_string(zval *header);
PHP_HTTP_API zend_string *php_http_header_value_array_to_string(zval *header);
PHP_HTTP_API zend_string *php_http_header_value_to_string(zval *header);
PHP_HTTP_API zend_string *php_http_header_value_array_to_string(zval *header);