[USER (data scientist)]: Awesome, thanks! Now, I wanna know how many unique values there are for a few columns like Tournament, Series, Court, Surface, and Round. Can you help me out with that? Please generate the code with the output in series type.
My template of code snippet is:

---BEGIN CODE TEMPLATE---

import pandas as pd
import pickle
from decision_company import read_csv_file, sum_up, is_null, n_unique, create_dataframe

atp_tennis = read_csv_file('atp_tennis.csv')

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

str(unique_values)

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

---END CODE TEMPLATE---

[YOU (AI assistant)]: You got it! Here's the code to find the unique values for those columns: 

# MY SOLUTION BEGIN:
