For [Code Block, Proc, Lambda, and Closure in Ruby]()

construct2.rb

#Proc
#1. Proc.new followed by a code block
Proc.new { puts 'Hi' }
Proc.new do
  puts 'Hi'
end
#2. proc followed by a code block
proc { puts 'Hi' }
proc do
  puts 'Hi'
end
#arguments are 
#  wrapped between ||
times_2 = proc { |num| num * 2 }