#---
# Excerpted from "The ThoughtWorks Anthology",
# published by The Pragmatic Bookshelf.
# Copyrights apply to this code. It may not be used to create training material, 
# courses, books, articles, and the like. Contact us if you are in doubt.
# We make no guarantees that this code is fit for any purpose. 
# Visit http://www.pragmaticprogrammer.com/titles/twa for more book information.
#---
# using global functions with no identifiers


item(:secure_air_vent)

item(:acid_bath)
uses(:acid_bath, acid(:acid_bath_acid))
acid_type(:acid_bath_acid, :hcl)
acid_grade(:acid_bath_acid, 5)
uses(:acid_bath, electricity(12))

item(:camera)
uses(:camera, electricity(1))

item(:small_power_plant)
provides(:small_power_plant, electricity(11))
depends(:small_power_plant, :secure_air_vent)