Refactor options' checkers so they are explicitly compared to nil when given in a list

lib/exw3.ex

@@ -550,16 +550,9 @@ defmodule ExW3 do
     # Options' checkers
 
     defp check_option(nil, error_atom), do: {:error, error_atom}
-
     defp check_option([], error_atom), do: {:error, error_atom}
-    defp check_option([head | tail], atom) do
+    defp check_option([head | tail], atom) when head != nil,  do: {:ok, head}
-      if head do
+    defp check_option([_head | tail], atom), do: check_option(tail, atom)
-        {:ok, head}
-      else
-        check_option(tail, atom)
-      end
-    end
-
     defp check_option(value, _atom), do: {:ok, value}
 
     # Casts