those `!= nil` is not neccessery, nil is like false

```ruby
gotar@air ~ $ irb
2.0.0-p247 :001 > a = true
 => true
2.0.0-p247 :002 > b = nil
 => nil
2.0.0-p247 :003 > a && b
 => nil
2.0.0-p247 :004 > a || b
 => true
2.0.0-p247 :005 > nil && nil
 => nil
2.0.0-p247 :008 > puts 'a' if a || b
a
 => nil
2.0.0-p247 :009 > puts 'a' if a && b
 => nil
```