Another block example for you

block.rb

def create_tag(tag, **args)
  attributes = args.map { |k,v| " #{k}=\"#{v}\"" }.join
  block = yield if block_given?
  "<%s%s>%s</%s>" % [tag, attributes, block, tag]
end

example.rb

link_1 = create_tag(:a, {href: "#", title: "My link"})

link_2 = create_tag(:a, {href: "#", title: "My link"}) do
  'Link Text'
end

link_3 = create_tag(:a, {href: "#", title: "My link"}) do
  create_tag(:span) do 
    'inside text'
  end
end

puts link_1
#=> <a href="#" title="My link"></a>
puts link_2
#=> <a href="#" title="My link">Link Text</a>
puts link_3
#=> <a href="#" title="My link"><span>inside text</span></a>