Added UStack to ufpy:

ufpy/ustack.py

@@ -0,0 +1,80 @@
+# -*- encodibg: utf-8 -*-
+from __future__ import annotations
+from typing import Any
+
+class UStackElement():
+    def __init__(self, value: Any) -> UStackElement:
+        """
+        UStackElement is using like an element in UStack.
+        """
+        self.__value: Any = value
+
+    def __len__(self):
+        return len(self.__value)
+
+    def __str__(self):
+        return str(self.__value)
+
+    def __int__(self):
+        return int(self.__value)
+
+    def __bool__(self):
+        return bool(self.__value)
+
+    def __dict__(self):
+        return dict(self.__value)
+
+    def __bytes__(self, encoding: str = 'utf-8'):
+        return bytes(self.__value, encoding)
+
+class UStack():
+    def __init__(self, _list: list | tuple = list()) -> UStack:
+        """
+        UStack's methods:
+            append(**items) - to add item to begin.
+            empty() - true if stack is empty.
+            pop() - delete the last element in stack.
+        """
+        if len(_list) != 0:
+            self.__list = [UStackElement(item) for item in _list]
+        else:
+            self.__list = _list
+
+    def append(self, *items) -> UStackElement:
+        for item in items:
+            item = UStackElement(item)
+            self.__list.append(item)
+        return items
+
+    def empty(self) -> bool:
+        return len(self.__list) == 0
+
+    def pop(self) -> UStackElement | None:
+        if not self.empty():
+            item: UStackElement = self.__list[-1]
+            del self.__list[-1]
+            return item
+        else:
+            return None
+
+    def top(self) -> UStackElement | None:
+        if not self.empty():
+            return self.__list[-1]
+        else:
+            return None
+
+    def __add__(self, stack: UStack) -> UStack:
+        return UStack(self.__list + stack.__list)
+
+    def __radd__(self, stack: UStack) -> UStack:
+        return UStack(stack.__list + self.__list)
+
+    def __len__(self) -> int:
+        return len(self.__list)
+
+s = UStack()
+s.append(1, 2, 3, 4, 6)
+s2 = UStack()
+s2.append(1, 2, 3, 4, 5)
+s3 = s + s2
+print(s3.top())