# L-21 MCS 260 : a stack
"""
Definition of a module to store a stack
of some data.
"""
from stack_data import STACK

def push(item):
    """
    pushes the item on the stack
    """
    STACK.insert(0, item)

def length():
    """
    returns the length of the stack
    """
    return len(STACK)

def pop():
    """
    returns an item off the stack
    """
    return STACK.pop(0)