d3_selectionPrototype.property = function(name, value) {

  // If no value is specified, return the first value.

  if (arguments.length < 2) return this.node()[name];

  function propertyNull() {

    delete this[name];

  }

  function propertyConstant() {

    this[name] = value;

  }

  function propertyFunction() {

    var x = value.apply(this, arguments);

    if (x == null) delete this[name];

    else this[name] = x;

  }

  return this.each(value == null

      ? propertyNull : (typeof value === "function"

      ? propertyFunction : propertyConstant));

};