[curlopt_encoding] is used together with [curl->set]. The parameter expected by [curl->set] is a string that sets the contents of the Accept-Encoding: header sent in an HTTP request, and enables decoding of a response when a Content-Encoding: header is received. Three encodings are supported: identity, which does nothing, deflate which requests the server to compress its response using the zlib algorithm, and gzip which requests the gzip algorithm. If a zero-length string is set, then an Accept-Encoding: header containing all supported encodings is sent.