import pandas as pd

# Assert that country does not contain any missing values
assert pd.notnull(gapminder.country).all()

# Assert that year does not contain any missing values
assert pd.notnull(gapminder.year).all()

# Drop the missing values
gapminder = gapminder.dropna(axis = 0, how = 'any')

# Print the shape of gapminder
print(gapminder.shape)
