Convert object into a read-only (frozen) variant. Well, to the extent possible.

freeze.py

from functools import singledispatch
from types import MappingProxyType

@singledispatch
def freeze(obj):
    """Convert obj into a read-only (frozen) variant. Well, to the extent possible."""
    """ Example: foo = freeze({"x": [1,2,{3,4}]})
    """
    return obj # not much frost today

@freeze.register(tuple)
@freeze.register(list)
def freeze_list(obj):
    return tuple(freeze(x) for x in obj)

@freeze.register(set)
@freeze.register(frozenset)
def freeze_set(obj):
    return frozenset(freeze(x) for x in obj)

@freeze.register(dict)
@freeze.register(MappingProxyType)
def freeze_dict(obj):
    return MappingProxyType({k: freeze(v) for k, v in obj.items()})