code: function assertObjectMapOf(valueValidatorFn, value, name, description) {
    if (!underscore.isObject(value)) {
      throw new Error(
          '<' + value + '> is not an Object map, ' + name + ': ' + description);
    }
  
    // Check all values.
    for (var key in value) {
      valueValidatorFn(value[key], name + '[\'' + key + '\']', description);
    }
  }
docs: Throws an Error if value isn't an Object, and invokes elementValidatorFn for
  each value within the map.
  @param {function(*, string, string)} valueValidatorFn
  @param {*} value
  @param {string} name The option name.
  @param {string} description Description of the option.