Calculate dynamic size using free cash in from_signals function

[nancyliu1203]

I'd like to calculate size using available free cash (not init_cash) in from_signals function, is there a way to do so? I know this can be achieved using from_order_func function, but wondering can this be achieved using from_signals function?

I searched around and found out this answer to manipulate order-related info. However, how can I access free cash (which is not in SignalContext) in signal_func_nb?