I need to use a function in order to get a return instead printing the output
<p>A catering company has hired you to help with organizing and preparing customer's orders. You are given a list of each customer's desired items, and must write a program that will count the number of each items needed for the chefs to prepare. The items that a customer can order are: salad, hamburger, and water.</p>

<p>Write a function called item_order that takes as input a string named order. The string contains only words for the items the customer can order separated by one space. The function returns a string that counts the number of each item and consolidates them in the following order: salad:[# salad] hamburger:[# hambruger] water:[# water] </p>

<p>If an order does not contain an item, then the count for that item is 0. </p>

<p>Notice that each item is formatted as [name of the item][a colon symbol][count of the item] and all item groups are separated by a space.</p>

<p>For example:</p>

<p>• If order = "salad water hamburger salad hamburger" then the function returns "salad:2 hamburger:2 water:1"
• If order = "hamburger water hamburger" then the function returns "salad:0 hamburger:2 water:1"</p>

<p>This is the code so far:</p>

<pre><code>s = '"hamburger water hamburger water salad "'
#The value of s will be received by the user only with the options in s

subs = 'salad'

count =0
flag=True
start=0
while flag:
    a = s.find(subs,start)  

    if a==-1:          
        flag=False
    else:               
        count+=1        
        start=a+1
if count==0:
    salad="salad:0"
else:    
        b=str(count)   
        c=subs+':'
        salad=c+b 


subs = 'water'

count =0
flag=True
start=0
while flag:
    a = s.find(subs,start)  

    if a==-1:          
        flag=False
    else:               
        count+=1        
        start=a+1
if count==0:
    water="water:0"
else:      

        b=str(count)   
        c=subs+':'
        water=c+b 



subs = 'hamburger'


count =0
flag=True
start=0
while flag:
    a = s.find(subs,start)  

    if a==-1:          
        flag=False
    else:               
        count+=1        
        start=a+1
if count==0:
    hamburger="hamburger:0"
else:
        b=str(count)   
        c=subs+':'
        hamburger=c+b 


print salad,hamburger,water
</code></pre>