Python 3.x yaml.safe_load返回字符串而不是对象

我有一段代码：

    config_object = yaml.safe_load(config_string)
    print("passed config: {}".format(config_object)) 
    ^^ prints expected yaml structure

    print("deserialized config object type: {}".format(type(config_object)))
    ^^ prints deserialized config object type: <class 'str'>

    value = config_object["field1"]["field2"]["field3"]
    ^^  Error: string indices must be integers

---

我不明白为什么字符串被返回。我在这里看不到任何字符串返回类型：

您的示例对我适用：您的示例对我适用：

   ---
   field1:
     field2:
       field3: value
     field4: value
   ...