code: function firstOrDefault(predicate, defaultValue) {
    predicate = typeof predicate === 'function' ? predicate : util.defaultPredicate;
  
    for (let item of this) {
      if (predicate(item)) return item;
    }
  
    return defaultValue;
  }
docs: Returns the first element of the sequence that satisfies a condition or a default value if no such element is found.
  
  @param {(Function)} predicate The function called per iteraction till returns true.
  @param defaultValue The default value.