# A square with a circle inside, represents a machine
handle: name $x+w/2$ $y-4$ middle
<rect x="$x$" y="$y$" width="$w$" height="$h$" fill="lightblue" stroke="black" stroke-width="1"/>
<circle cx="$x+w/2$" cy="$y+h/2$" r="$w/3$" fill="blue"/>