If you don’t have Tim Pope’s unimpaired.vim, you should. Unimpaired adds many useful pairs of mappings including one for adding an empty line above or below your current line.
In normal mode, use
]<Space> to add an empty line either above
or below your current line. With your cursor on the def bar line below, tap
[<Space> and a line will be effortlessly inserted above while your cursor remains
on its line.