code: function css_string(css_object) {
      var result = "";
      if ("object" == typeof css_object) {
          for (var key in css_object) {
              result += key + ":" + css_object[key] + ";";
          }
      }
      return result;
  }
docs: takes an object like {"top": "10px", "left": "5px"} and return a string like "top: 10px; left: 5px;"