Human: What is a good Python program to return then values of a column in a data frame. Assistant: 
Here is a Python program to return then values of a column in a data frame

import pandas as pd

def return_nan_values(df):
    """
    Return nan values of a column in data frame.
    """
    return df.isnull().sum()

# Enter the data
df = pd.DataFrame({'a': [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 'b': [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]})

# Calling the function
print((return_nan_values(df)))

#Example Output
# a    0
# b    0
# dtype: int64

#Remember to inspect code for bugs.