implement buy, which takes a list of required$\_$fruits $($strings$),$ a dictionary prices $($strings for key, positive integers for value$),$ and a total$\_$amount $($integer$).$ It prints all the ways to buy some of each required fruit so that the total price equals total$\_$amount. You must include at least one of every fruit in required$\_$fruit and cannot include any other fruits that are not in required$\_$fruit.

The display function will be helpful. You can call display on a fruit and its count to create a string containing both.

What does fruits and amount represent? How are they used in the recursive?

def buy$($required$\_$fruits, prices, total$\_$amount$)$:

$"""$Print ways to buy some of each fruit so that the sum of prices is amount.

$>>>$ prices $=\{\text{'}$oranges$\text{'}$: $4,$ 'apples': $3,$ 'bananas': $2,$ 'kiwis': $9\}$

$>>>$ buy$([\text{'}$apples$\text{'},$ 'oranges', 'bananas'$],$ prices, $12)$

$[2$ apples$][1$ orange$][1$ banana$]$

$>>>$ buy$([\text{'}$apples$\text{'},$ 'oranges', 'bananas'$],$ prices, $16)$

$[2$ apples$][1$ orange$][3$ bananas$]$

$[2$ apples$][2$ oranges$][1$ banana$]$

$>>>$ buy$([\text{'}$apples$\text{'},$ 'kiwis'$],$ prices, $36)$

$[3$ apples$][3$ kiwis$]$

$[6$ apples$][2$ kiwis$]$

$[9$ apples$][1$ kiwi$]$

$"""$

def add$($fruits$,$ amount, cart$)$:

if fruits $==[]$ and amount $==0$:

print$($cart$)$

elif fruits and amount $>0$:

fruit $=$ fruits$[0]$

price $=\_\_\_\_$

for k in $\_\_\_\_$:

add$(\_\_\_\_,\_\_\_\_,\_\_\_\_)$

add$($required$\_$fruits, total$\_$amount, $\text{'}\text{'})$

def display$($fruit$,$ count$)$:

$"""$Display a count of a fruit in square brackets.

$>>>$ display$(\text{'}$apples$\text{'},3)$

$\text{'}[3$ apples$]\text{'}$

$>>>$ display$(\text{'}$apples$\text{'},1)$

$\text{'}[1$ apple$]\text{'}$

$"""$

assert count $>=1$ and fruit$[-1]==\text{'}$s$\text{'}$

if count $==1$:

fruit $=$ fruit$[$:$-1]$ # get rid of the plural s

return $\text{'}[\text{'}+$ str$($count$)+\text{'}\text{'}+$ fruit $+\text{'}]\text{'}$