Lesson 18 - Print Airplane faa_id

Hi there,

I noticed at the end of Lesson 18 the additional class parameter for Airplane was introduced (faa_id), but I can't seem to print out that information like the others. VScode doesn't seem to like cessna.faa_id() and labels it as TypeError: 'str' object is not callable (when executed). 

Has anyone figured that out?