:sig
bool ws_is_binary()

:params
return value : true if the current WebSocket message is binary

:see
>websocket

:content
Returns whether the message currently being handled by `WS(Request& context)` arrived as a binary frame.

If this returns `false`, the current message was delivered as a text frame.

:example
print(ws_is_binary() ? "binary frame" : "text frame (default outside a WS handler)", "\n");
