if(condition, clauses)

if( true, [do: "true staff", else: "false staff"]) # => "true staff"

if( true, [{:do, "true staff"}, {:else, "false staff"}]) # => "true staff"

var = "true staff"
if( true, [{:do, var}, {:else, "false staff"}]) # => "true staff"

var = {:do, "true staff"}
if( true, [var, {:else, "false staff"}])

** (ArgumentError) invalid or duplicate keys for if, only "do" and an optional "else" are permitted
   (elixir) lib/kernel.ex:2569: Kernel.build_if/2
   (elixir) expanding macro: Kernel.if/2
            iex:18: (file)

var = {:do, "true staff"}
[var] # => [do: "true staff"]