PHP_HTTP_API void php_http_header_to_callback(HashTable *headers, zend_bool crlf, php_http_pass_format_callback_t cb, void *cb_arg TSRMLS_DC);
PHP_HTTP_API void php_http_header_to_string(php_http_buffer_t *str, HashTable *headers TSRMLS_DC);
PHP_HTTP_API void php_http_header_to_callback(HashTable *headers, zend_bool crlf, php_http_pass_format_callback_t cb, void *cb_arg TSRMLS_DC);
PHP_HTTP_API void php_http_header_to_string(php_http_buffer_t *str, HashTable *headers TSRMLS_DC);