Valve foo_valve [Foo] import foo foo.valve(item_size=$type.size*$vlen, open=bool($open)) set_open(bool($open)) Type type enum Complex complex size:gr.sizeof_gr_complex Float float size:gr.sizeof_float Int int size:gr.sizeof_int Short short size:gr.sizeof_short Byte byte size:gr.sizeof_char Open open 0 raw Vec Length vlen 1 int $vlen > 0 in $type $vlen $num_inputs out $type $vlen $num_outputs Connect output to input when valve is closed (not open).