#@title Exercise: implement $\text{'}\text{'}$ for a counting queue

def countingqueue$\_$len$($self$)$:

$"""$Returns the number of elements in the queue."""

### YOUR SOLUTION HERE

# This is a way to add a method to a class once the class

# has already been defined.

CountingQueue.$\_=$ countingqueue$\_$len

$[]$ # Tests $10$ points: $\text{'}$

$q=$ CountingQueue$()$ for $i$ in range$(10)$: $,q*add{(}^{\text{'}}{a}^{\text{'}})q*$ add$(\text{'}$b$\text{'})$ for $i$ in range$(3)$: q$.$add$(\text{'}$c$\text{'},$ count$=2)$ check equal$($len $(q),17$