execution order of trait observers about traitlets HOT 2 OPEN

class Test(tr.HasTraits):
    c = tr.Bool(default_value=True)
    b = tr.Bool(default_value=True)
    a = tr.Bool(default_value=True)

    @tr.observe("a")
    def _a(self, on_change):
        print(f"a = {self.a}")

    @tr.observe("b")
    def _b(self, on_change):
        print(f"b = {self.b}")

    @tr.observe("c")
    def _c(self, on_change):
        print(f"c = {self.c}")

    @classmethod
    def trait_order(cls):
        return [k for k, v in cls.__dict__.items() if isinstance(v, tr.TraitType)]

    def __init__(self, **kwargs):
        super().__init__()
        kwargs = self.get_ordered_kwargs(kwargs)
        {setattr(self, k, v) for k, v in kwargs.items()}

    def get_ordered_kwargs(self, kwargs):
        in_order = list(kwargs.keys())
        tr_order = self.trait_order()
        out_order = tr_order + [i for i in in_order if i not in tr_order]
        return {o: kwargs[o] for o in out_order}


t1 = Test(a=False, b=False, c=False)
print("---")
t2 = Test(c=False, b=False, a=False)

# c = False
# b = False
# a = False
# ---
# c = False
# b = False
# a = False

class Test(tr.HasTraits):
    trait = tr.Bool(default_value=True)

    @tr.observe("trait")
    def _b(self, on_change):
        print("From _b")

    @tr.observe("trait")
    def _c(self, on_change):
        print("From _c")

    @tr.observe("trait")
    def _a(self, on_change):
        print("From _a")

t = Test()

t.trait = False

# From _a
# From _b
# From _c