5. Give two identical dataframes Salesl6 and Salesl7. But Salesl7 has some values missing. Write code so that Salesl7 fills its missing values from corresponding entries of Salesl6.

import pandas as pd, numpy as np

Sales16 = pd.DataFrame({‘revenue’: [100, 200, 250, 275, 300, 350]})

Sales17 = pd.DataFrame({‘revenue’: [100, 200, np.nan, 275, np.nan, 350]})

print(Sales17.combine_first(Sales16)) # combine_first used to fill the missing values of Sales17 with the corresponding values of Sales16