class Person
  def initialize(@name)
  end

  def greet
    puts "Hi, I'm #{@name}"
  end
end

class Employee < Person
end

employee = Employee.new "John"
employee.greet #=> "Hi, I'm John"
employee.is_a?(Person) #=> true

@[Link("m")]
lib C
  # In C: double cos(double x)
  fun cos(value : Float64) : Float64
end

C.cos(1.5_f64) #=> 0.0707372

if "Hello" =~ /hello/i
  p %<world<["hello">>
end