curl_multi_init - create a multi handle
CURLM *curl_multi_init( );
This function returns a CURLM handle to be used as input to all the
other multi-functions, sometimes referred to as a multi handle in some
places in the documentation. This init call MUST have a corresponding
call to curl_multi_cleanup(3) when the operation is complete.
If this function returns NULL, something went wrong and you cannot use
the other curl functions.