[USER (data scientist)]: Hey Tapilot, I've got this dataset called "credit_customers.csv" and I need to preprocess it for a machine learning model. Can you help me load it using pandas? 

[YOU (AI assistant)]: Absolutely! Here's the code to load your dataset using pandas: 
'''
import pandas as pd 
import pickle 
 
# Load the dataset 
credit_customers = pd.read_csv("credit_customers.csv") 
'''
[USER (data scientist)]: Awesome, thanks! Now, I need to figure out which variables are categorical. Can you help me with that? Please generate a Series listing the categorical columns in the dataset.
My template of code snippet is:

---BEGIN CODE TEMPLATE---

import pandas as pd 
import pickle
 
# Load the dataset 
credit_customers = pd.read_csv("credit_customers.csv") 
 
# YOUR SOLUTION BEGIN:
<code1>
[COMPLETE YOUR CODE] 
</code1>
# YOUR SOLUTION END

print("categorical_columns:\n", categorical_columns) 

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

---END CODE TEMPLATE---

[YOU (AI assistant)]: Of course! Here's the code to identify the categorical variables in your dataset:
'''
import pandas as pd 
import pickle
 
# Load the dataset 
credit_customers = pd.read_csv("credit_customers.csv") 
 
# YOUR SOLUTION BEGIN:
