Add @spec for Enum.sort_by/3
Add @spec for Enum.sort_by/3

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