gistfile1.rb

#!/usr/bin/env ruby

module M
  refine NilClass do # !> Refinements are experimental, and the behavior may change in future versions of Ruby!
    def magic
      "some magic stuff is happening"
    end
  end
end

class Hohooo
  
end


howdy = Hohooo.new # => #<Hohooo:0x007fc55210c4c0>

howdy.instance_eval("using M\nnil.magic") # => 

# ~> -:18:in `instance_eval': undefined method `using' for #<Hohooo:0x007f98ac21c4f0> (NoMethodError)
# ~> 	from -:18:in `instance_eval'
# ~> 	from -:18:in `<main>'

eval("using M\nnil.magic") # => "some magic stuff is happening"