from typing import Any

class Stack:

def __init__(self, capacity: int = 10) -> None:

self.stack = []

self.capacity = capacity

def __len__(self):

"""

>>> stack = Stack()

>>> for i in range(0, 10):

... stack.push(i)

>>> len(stack)

10

"""

return len(self.stack)

def size(self) -> int:

"""

>>> stack = Stack()

>>> for i in range(0, 10):

... assert len(stack) == i

... stack.push(i)

>>> stack.size()

10

"""

return len(self)

def is_full(self) -> bool:

"""

>>> stack = Stack()

>>> for i in range(0, 10):

... stack.push(i)

>>> stack.is_full()

True

"""

return len(self) == self.capacity

def is_empty(self) -> bool:

"""

>>> stack = Stack()

>>> stack.is_empty()

True

>>> stack.push(666)

>>> stack.push(999)

>>> stack.is_empty()

False

"""

return len(self) == 0

def push(self, item: Any) -> None:

"""

>>> stack = Stack()

>>> for i in range(0, 10):

... stack.push(i)

>>> stack.push(666)

Traceback (most recent call last):

...

ValueError: stack is full

"""

if self.is_full():

raise ValueError("stack is full")

self.stack.append(item)

def pop(self) -> Any:

"""

>>> stack = Stack()

>>> stack.pop()

Traceback (most recent call last):

...

ValueError: stack is empty

>>> for i in range(0, 10):

... stack.push(i)

>>> for i in range(9, -1, -1):

... assert stack.pop() == i

"""

if self.is_empty():

raise ValueError("stack is empty")

return self.stack.pop()

def peek(self) -> Any:

"""

>>> stack = Stack()

>>> stack.peek()

Traceback (most recent call last):

...

ValueError: stack is empty

>>> stack.push('a')

>>> stack.push('b')

>>> stack.push('c')

>>> stack.peek()

'c'

"""

if self.is_empty():

raise ValueError("stack is empty")

return self.stack[-1]

if __name__ == "__main__":

from doctest import testmod

testmod()