[Fix][PT] - Concurrencies (#1401)
[Fix][PT] - Concurrencies (#1401)

Some typos and improvements.
doomspork/elixir-school,nscyclone/elixir-school,nscyclone/elixir-school,doomspork/elixir_school,nscyclone/elixir-school,doomspork/elixir-school,doomspork/elixir_school,doomspork/elixir_school,nscyclone/elixir-school,doomspork/elixir-school