Some customer records have no city. Before planning delivery zones, the data team wants to know which countries are affected.
From customers.csv, store the number of customers with a missing city in each country, as a Series. Leave out countries with none missing.
Expected answer
Store your answer in result.
Hints, the later steps and the answer come with Pro.
import pandas as pd
customers = pd.read_csv("customers.csv")
result = ...