What does the "!!" symbol mean in Ruby?

Question

def test
!!session[:test]
end

!! - what does this do? can we remove it and still assume it will work the same?

Answer 1

That would be the double bang (or bang bang).

It's not really an operator in itself. It is really two ! operators together...which performs double negation. It is used to make sure you're working with a boolean value.