# def timer
#   start_time = Time.now
#   yield
#   puts "Elapsed time: #{Time.now - start_time}s"
# end

# # def timer2
# #   start_time = Time.now
# #   (1..8000000).to_a.each {|n|}
# #   puts "Elapsed time: #{Time.now - start_time}s"
# # end

# # result = timer do |message|
# #   puts message
# #   sleep(2)
# # end

# # puts result
# puts "how many iterations"
# count = gets.chomp.to_i

# result = timer do
#   (1..count).to_a.each {|n|}
# end

# puts result

def say_hello(first_name, last_name)
  full_name = "#{first_name} #{last_name}"
  puts yield(full_name) if block_given?
end

say_hello("Charles", "Brownson")


say_hello("Johnny", "Hallyday") do |name|
  "Hi #{name}"
end