await_body(ConnPid, StreamRef)
    -> await_body(ConnPid, StreamRef, 5000, MonitorRef)

await_body(ConnPid, StreamRef, MonitorRef)
    -> await_body(ConnPid, StreamRef, 5000, MonitorRef)

await_body(ConnPid, StreamRef, Timeout)
    -> await_body(ConnPid, StreamRef, Timeout, MonitorRef)

await_body(ConnPid, StreamRef, Timeout, MonitorRef)
    -> {ok, Body} | {ok, Body, Trailers} | {error, Reason}

ConnPid    :: pid()
StreamRef  :: gun:stream_ref()
MonitorRef :: reference()
Timeout    :: timeout()
Body       :: binary()
Trailers   :: [{binary(), binary()}]
Reason     :: {stream_error | connection_error | down, any()}
            | timeout

StreamRef = gun:get(ConnPid, "/articles", [
    {<<"accept">>, <<"text/html;q=1.0, application/xml;q=0.1">>}
]).
{response, nofin, 200, _Headers} = gun:await(ConnPid, StreamRef).
{ok, _Body} = gun:await_body(ConnPid, StreamRef).