diff --git a/collections_extended/dict_extended.py b/collections_extended/dict_extended.py
new file mode 100644
index 0000000..b97a5b4
--- /dev/null
+++ b/collections_extended/dict_extended.py
@@ -0,0 +1,79 @@
+from collections.abc import MutableMapping
+from typing import Any, Iterable
+
+from .sentinel import NOT_SET
+
+# * MultiDict
+# * Ordered / Indexed
+# * frozen
+# * bijection
+
+class DictExtended(MutableMapping):
+
+	__slots__ = ('_data', )
+
+	def __init__(self, iterable: Iterable, default: Any = NOT_SET, **kwargs):
+		self._data = {}
+		self.default = default
+		self.update(iterable, **kwargs)
+
+	def _default_value(self):
+		try:
+			return self.default()
+		except TypeError:
+			# default is not Callable
+			return self.default
+
+	def __len__(self):
+		return len(self._data)
+
+	def __getitem__(self, key):
+		try:
+			return self._data[key]
+		except KeyError:
+			if self.default is NOT_SET:
+				raise
+			else:
+				return  elf._default_value()
+
+	def __setitem__(self, key, value):
+		self._data[key] = value
+
+	def __delitem__(self, key):
+		del self._data[key]
+
+	def __contains__(self, key):
+		return key in self._data
+
+	def get(self, key, default=None):
+		try:
+			return self._data[key]
+		except KeyError:
+			return default
+
+	def pop(self, key, default=NOT_SET):
+		raise NotImplementedError
+
+	def popitem(self):
+		raise NotImplementedError
+
+	def clear(self):
+		self._data.clear()
+
+	def update(self, other=None, /, **kwargs):
+		raise NotImplementedError
+
+	def setdefault(self, key, default=None):
+		raise NotImplementedError
+
+	def keys(self):
+		return self._data.keys()
+	
+	def items(self):
+		return self._data.items()
+
+	def values(self):
+		return self._data.values()
+
+	def __eq__(self, other):
+		raise NotImplementedError