code: function (subpath) {
      var subpathAsArray = asArrayPath(subpath);
      if (!Util.undefinedOrNull(this.get(subpathAsArray))) {
        update(this, subpathAsArray, clear);
      }
      return this;
    }
docs: Clear nested collection. Does '.clear()' on Immutable values, nullifies otherwise.
  @param {String|Array} [subpath] subpath as a dot-separated string or an array of strings and numbers
  @return {Binding} this binding