handle namedtuples

[lucsorel]

• the _fields attribute enables to detect classes defined with the collections.namedtuple factory method, its keys are the class attributes
• the attributes are not typed: specify any or don't specify one

from collections import namedtuple

Circle = namedtuple('Circle', ['x', 'y', 'radius'], defaults=[1])

# Circle._fields: ('x', 'y', 'radius')
# Circle._fields_defaults: {'radius': 1}