python tip

There's a standard way to get a list of unique values for a particular column: clients['state'].unique(). However, if you have a huge dataset with millions of entries, you might prefer a much faster option:

# Checking unique values efficiently
clients['state'].drop_duplicates(keep="first", inplace=False).sort_values()

This way, you drop all the duplicates and keep only the first occurrence of each value. We've also sorted the results to check that each state is indeed mentioned only once.