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