Interface $valuesBeta

interface $values {
    circo: "circo";
    dot: "dot";
    fdp: "fdp";
    neato: "neato";
    nop: "nop";
    nop2: "nop2";
    osage: "osage";
    patchwork: "patchwork";
    sfdp: "sfdp";
    twopi: "twopi";
}