Interactive Ruby

irb(main):001:0> n = 5
=> 5
irb(main):002:0> def fact(n)
irb(main):003:1>   if n <= 1
irb(main):004:2>     1
irb(main):005:2>   else
irb(main):006:2*     n * fact(n - 1)
irb(main):007:2>   end
irb(main):008:1> end
=> :fact
irb(main):009:0> fact(n)
=> 120

irb(main):001:0> class Cat
irb(main):002:1>   def meow
irb(main):003:2>     puts 'The cat meows.'
irb(main):004:2>   end
irb(main):005:1> end
=> :meow

irb(main):006:0> Cat.new.meow
The cat meows.