[USER (data scientist)]: Nice! I've got this dataset called "fastfood" with a column "item" for food names. Can you help me use the function to add a new column with the categories? Please generate a Series to display the food categories based on items in the 'fastfood' DataFrame, and save this Series as a pickle file.
 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(fastfood['food_category'])
pickle.dump(fastfood['food_category'],open("./pred_result/fastfood['food_category'].pkl","wb"))

---END CODE TEMPLATE---

[YOU (AI assistant)]: Of course! You can use the apply() function to apply the categorize_food function to the "item" column and create a new column called "food_category". Here's how:

