Added "freeze" function to create immutable copies of mutable objects.

lib/Bastion/Common.py

@@ -12,6 +12,13 @@
 import pathlib
 import logging
 import urllib
+from functools import singledispatch
+from types import MappingProxyType
+
+try:
+	from frozendict import frozendict
+except ImportError:
+	frozendict = lambda d: MappingProxyType(d)
 
 from typing import Any, FrozenSet
 
@@ -487,3 +494,26 @@ def asInteger(x):
 
 def asNumeric(x):
 	return float(x)
+
+@singledispatch
+def freeze(obj):
+	"""
+	An outer function that takes a generic object and attempts to build an immutable version of the given object.
+	"""
+	return obj  # default: assume immutable
+
+@freeze.register
+def _(obj: dict):
+	return frozendict({freeze(k): freeze(v) for k, v in obj.items()})
+
+@freeze.register
+def _(obj: list):
+	return tuple(freeze(i) for i in obj)
+
+@freeze.register
+def _(obj: set):
+	return frozenset(freeze(i) for i in obj)
+
+@freeze.register
+def _(obj: tuple):
+	return tuple(freeze(i) for i in obj)