function _mathChain(o, math, thisChain, nextChain, type) {
  for (var i in o.mathOps) {
    if (o.mathOps[i] instanceof type) {
      o.mathOps[i].dispose();
      thisChain = i;
      if (thisChain < o.mathOps.length - 1) {
        nextChain = o.mathOps[i + 1];
      }
    }
  }
  o.mathOps[thisChain - 1].disconnect();
  o.mathOps[thisChain - 1].connect(math);
  math.connect(nextChain);
  o.mathOps[thisChain] = math;
  return o;
}
Used by Osc and Envelope to chain signal math