title: be false vs be_falsey in rspec
body: <p>I know be false will just return true if the expected value is a pure false value, wherease be_falsey will return true if the expected value is either false or nil.</p>
  
  <p>However, I fail to understand when would I use one or the other. I fail to see an example where be_falsey would be more useful than be false.</p>