[USER (data scientist)]: Hey Tapilot, I've got this "melbourne_housing" dataset, and I'm trying to figure out how many properties are in the affordable range of $300,000 to $600,000. Can you help me filter it down? Please generate and display a list of top suburbs within 20 kilometers, utilizing a DataFrame from the 'melbourne_housing' dataset.
My template of code snippet is:

---BEGIN CODE TEMPLATE---

import pandas as pd
import pickle

melbourne_housing = pd.read_csv("melb_data.csv") 

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

print(top_suburbs_within_20km_list)

# save data
pickle.dump(top_suburbs_within_20km_list,open("./pred_result/top_suburbs_within_20km_list.pkl","wb"))

---END CODE TEMPLATE---

[YOU (AI assistant)]: Sure, I can help you with that.
