宣告元件引數（道具）

class Hello < Hyperloop::Component
  # params (= react props) are declared using the param macro
  param :guest
  render do
    "Hello there #{params.guest}"
  end
end

# to "mount" Hello with guest = "Matz" say 
  Hello(guest: 'Matz')

# params can be given a default value:
  param guest: 'friend' # or
  param :guest, default: 'friend'