from dataclasses import dataclass, field

@dataclass(order=True)
class Task:
    priority: int
    title: str
    tags: list[str] = field(default_factory=list)
    done: bool = False

    def finish(self):
        self.done = True

tasks = [Task(2, "Write tests"), Task(1, "Fix bug", ["urgent"])]
print(sorted(tasks))
tasks[0].finish()
print(tasks[0])

@dataclass(frozen=True)
class Colour:
    r: int
    g: int
    b: int

red = Colour(255, 0, 0)
print(red)

Fields with defaults come after fields without.
A list default must use field(default_factory=list): the same mutable default trap as before, and dataclasses refuse to let you fall into it.
order=True adds <, > and friends, comparing fields in order, so objects can be sorted.
frozen=True makes objects immutable: assigning to a field raises an error. Frozen data classes can be dictionary keys and set members.