[USER (data scientist)]: Great, now perform K-means clustering with 4 clusters and add the cluster labels back to the original dataset. Please generate the code with the output in dataframe type.
My template of code snippet is:

---BEGIN CODE TEMPLATE---

import pandas as pd  
from sklearn.cluster import KMeans 
import pickle
from decision_company import read_csv_file, create_kmeans, fit_predict_kmeans, col_assign_val

# Load the dataset  
credit_customers = read_csv_file("credit_customers.csv")  
  
# YOUR SOLUTION BEGIN:
<code1>
[GENERATE YOUR CODE]  
</code1>
# YOUR SOLUTION END

print("credit_customers:\n", credit_customers)    

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

---END CODE TEMPLATE---

[YOU (AI assistant)]: Sure thing! Here's the code to perform K-means clustering and add the cluster labels:

# MY SOLUTION BEGIN:
