def __init__(self, attr_type=None, attr=None, required=True, **kwargs):
"""Attribute constructor.
:param attr_type: Type, Schema or constant that does the type conversion of the attribute.
:param attr: Attribute name, dot-separated attribute path or an `Accessor` instance.
:param required: Is attribute required to be present.
"""
self.attr_type = attr_type or types.Type()
self.attr = attr
self.required = required
if "default" in kwargs:
self.default = kwargs["default"]
self.creation_counter = Attr.creation_counter
Attr.creation_counter += 1
def test_type():
"""Test very basic."""
type_ = types.Type()
value = object()
assert value is type_.serialize(value)
assert value is type_.deserialize(value)