Filtering two or more elements from a column

[thap2331]

Hi,
I am new to piping but I really want to start working using pipes.

I have a dataframe in which one of the column is country names. I want to mask only few countries.
I know we can do this if I want only one element. (df_world >> mask(X.Country=='Nigeria')).

But how do I select multiple countries from a column. For example, I want 'Nigeria' and 'China' only?