text: var d3_arraySubclass = [].__proto__?
  
  // Until ECMAScript supports array subclassing, prototype injection works well.
  function(array, prototype) {
    array.__proto__ = prototype;
  }:
  
  // And if your browser doesn't support __proto__, we'll use direct extension.
  function(array, prototype) {
    for (var property in prototype) array[property] = prototype[property];
  };
  