[USER (data scientist)]: Cool! Now, I'd like to calculate the win rate of Raonic M. against each of Federer's opponents. Can you help me with that? Please generate the code with the output in function type.
My template of code snippet is:

---BEGIN CODE TEMPLATE---

import pandas as pd
import numpy as np
import pickle
from decision_company import read_csv_file, fetch_column, logical_and, logical_or, create_dataframe, concatenate_objects, reset_index, search_where, extract_unique_values, update_dict, assert_series

# Load the dataset 
atp_tennis = read_csv_file('atp_tennis.csv')

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

---END CODE TEMPLATE---

[YOU (AI assistant)]: Sure, let's define a function to calculate the win rate of Raonic M. against a given opponent: 

# MY SOLUTION BEGIN:
