Improve assertion on function head test
Improve assertion on function head test

kelvinst/elixir,kelvinst/elixir,lexmag/elixir,michalmuskala/elixir,elixir-lang/elixir,pedrosnk/elixir,pedrosnk/elixir,ggcampinho/elixir,lexmag/elixir,kimshrier/elixir,ggcampinho/elixir,joshprice/elixir,kimshrier/elixir