Use dataclass

[foriequal0]

Depends on: #30

dataclass is better than NamedTuple

• You can override def __init__() and other methods
• It doesn't use a metaclass, so you can bring your own metaclass.
• It has a charming .asdict() that converts recursively as opposed to ugly namedtuple._asdict() that doesn't recurse.
• PyCharm doesn't complain that default items (statics) should be at the bottom of the definitions (False negative) when you want to add static variables (which is not default items).

[foriequal0]

pipenv don't install dataclasses; python_version < '3.7' on pipenv install --python 3.7 . if you put it only on setup.py.

[posgnu]

Seems nice.

[posgnu]

LGTM