min_dq.py

class MinDeque:
    '''As described in Exercise 3.16.'''

    def __init__():
        pass

    def __str__(self):
        '''Returns a string representation of an object for printing.
        '''
        pass

    def add_first(self, x):
        '''Adds x at the front.
        '''
        pass

    def add_last(self, x):
        '''Adds x at the back.
        '''
        pass

    def remove_first(self):
        '''Removes the element at the front and returns it. Returns None
        if dq is empty.
        '''
        pass

    def remove_last(self):
        '''Removes the element at the back and returns it. Returns None 
        if dq is empty.
        '''
        pass

    def size(self):
        '''Returns the number of elements currently in the dq.
        '''
        pass

    def min(self):
        '''Returns the smallest element currently in the dq.
        '''
        pass