<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def WriteSerialized(cls, attribute_container):
 """Writes an attribute container to serialized form. Args: attribute_container (AttributeContainer):
 attribute container. Returns: str: A JSON string containing the serialized form. """

    json_dict = cls.WriteSerializedDict(attribute_container)
    return json.dumps(json_dict)