What do you think gets printed as Exhibit F?

print_call_and_return.rb

#! /usr/bin/ruby

def print_call_and_return(string, &block)
  puts string
  block.call unless !block
  "return"
end

puts "=== exhibit A ==="

print_call_and_return("parameter")

puts "=== exhibit B ==="

a = print_call_and_return("parameter")
puts a

puts "=== exhibit C ==="

puts print_call_and_return("parameter")

puts "=== exhibit D ==="

print_call_and_return("parameter") do
  puts "block"
end

puts "=== exhibit E ==="

a = print_call_and_return("parameter") do
  puts "block"
end
puts a

puts "=== exhibit F ==="

puts print_call_and_return("parameter") do
  puts "block"
end