yield.rb

def timer
  start_time = Time.now
  puts 'starting a long algorithm....'
  yield
  puts 'process done!'
  end_time = Time.now
  return end_time - start_time
end

# timer do
#   sleep 2
# end
# puts time2

# time1 = timer do
#   sleep 1
# end
# puts time1
puts '------------'
def greet(first_name, last_name)
  full_name = "#{first_name.capitalize} #{last_name.upcase}"
  greeting = yield(full_name)
  return greeting
end

hi = greet('john', 'lennon') do |full_name|
  "Hello, #{full_name}"
end
puts hi

bonjour = greet('john', 'lennon') do |full_name|
  "Bonjour, #{full_name}"
end
puts bonjour