Correct gain.dsp example.

examples/gain.dsp

@@ -8,5 +8,5 @@ switch(i) = button("switch%i [switch:%i]") : hbargraph("[switchlight_red:%i]", 0
 // Gain slider, highlight in red
 gain(i) = hslider("gain%i [knob:%i]", 0.1, 0, 1, 0.01) : hbargraph("[light_red:%i]", 0, 1);
 
-process(x) = par(i, 6, x * gain(i+1) * (1-switch(i+1)));
+process = si.bus(6) : par(i, 6, *(gain(i+1)) * (1-switch(i+1)));