code: function _shallowCopyAttrs(src, dst) {
      if (Object.prototype.toString.call(src) !== '[object Object]') {
        throw new Error("Attributes are not an object: " + src);
      }
      for (var k in src) {
        dst[k] = src[k];
      }
    }
docs: Copies the first level of keys and values from src to dst.