$6.$ Implement a queue using two stacks. See below... $[2\mathrm{.}4$ hour challenge$]$

$```$

# Implement a queue using two stacks $...$

# More specifically, fill in the details where it says

# "add your code here" in the following code

# without using any additional storage.

class ChallengeStack:

def $\_\_$init$\_\_($self$)$:

self.data $=[]$

def push$($self$,$ value$)$:

self.data.append$($value$)$

def pop$($self$)$:

if len$($self$.$data$)==0$:

return None

r $=$ self.data$[-1]$

del self.data$[-1]$

return r

class ChallengeQueue:

def $\_\_$init$\_\_($self$)$:

$```$

$```$

self.s$2=$ ChallengeStack$()$

def put$($self$,$ value$)$:

pass # add your code here

def get$($self$)$:

pass # add your code here

# show the next element without removing it from the queue

def peek$($self$)$:

pass # add your code here

# returns the total number of elements in the queue

def size$($self$)$:

pass # add your code here

#Test your Queue implementation using the following $...$

q $=$ ChallengeQueue$()$

for i in range$(10)$:

assert q$.$size$()==$ i

q$.$put$($i$)$

assert q$.$size$()==$ i$+1$

assert q$.$peek$()==0$

for i in range$(5)$:

assert q$.$size$()==10-$i

assert q$.$peek$()==$ i

assert q$.$get$()==$ i

assert q$.$size$()==10-$i$-$

for i in range$(10)$:

assert q$.$size$()==$ i$+5$

q$.$put$($i$+10)$

assert q$.$size$()==$ i$+6$

assert q$.$peek$()==5$

$```$

for i in range$(15)$:

assert q$.$size$()==15-$i

assert q$.$peek$()==$ i$+5$

assert q$.$get$()==$ i$+5$

assert q$.$size$()==15-$i$-1$

Submit your python $.$py file to Moodle.