def __init__(self, attributes=None, tag=enums.Tags.ATTRIBUTES):
super(Attributes, self).__init__(tag=tag)<EOL>self._factory = AttributeValueFactory()<EOL>self._attributes = []<EOL>self.attributes = attributes<EOL>
Construct an Attributes structure.

Args:
    attributes (list): A list of attribute objects. Each object must
        be some form of primitive, derived from Base. Optional,
        defaults to None which is interpreted as an empty list.
    tag (enum): A Tags enumeration specifying what type of Attributes
        structure is in use. Valid values include:
            * Tags.ATTRIBUTES
            * Tags.COMMON_ATTRIBUTES
            * Tags.PRIVATE_KEY_ATTRIBUTES
            * Tags.PUBLIC_KEY_ATTRIBUTES
        Optional, defaults to Tags.ATTRIBUTES.