- content_for :demo do
  h1 This is content yielded from a content_for

.demo== yield_content :demo

- content_for :demo2 do |fname, lname|
  h1 This is content yielded with name #{fname + " " + lname}

.demo2== yield_content :demo2, "Johnny", "Smith"

.demo_has_content== content_for?(:demo)
.fake_has_content== content_for?(:fake)