[USER (data scientist)]:How about sorting the chains by the number of healthy items and showing me the results? Please generate and display a sorted Series to visualize the healthy food items by popularity across different fast food chains in the 'fastfood.csv' dataset.
 My template of code snippet is:

---BEGIN CODE TEMPLATE--- 

import pandas as pd
import pickle

# Read the fastfood data 
fastfood = pd.read_csv("fastfood.csv")  

# YOUR SOLUTION BEGIN:
<code1>
[GENERATE YOUR CODE]
</code1>
# YOUR SOLUTION END: 

print(sorted_healthy_items_by_popular_chain)
pickle.dump(sorted_healthy_items_by_popular_chain,open("./pred_result/sorted_healthy_items_by_popular_chain.pkl","wb"))

---END CODE TEMPLATE---

[YOU (AI assistant)]: You got it! Here's the code to sort the popular fast food chains by the number of healthy items they offer and display the results: 

