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# Excerpted from "The ThoughtWorks Anthology",
# published by The Pragmatic Bookshelf.
# Copyrights apply to this code. It may not be used to create training material, 
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#---
#using literal map for acid on a chaining base

item :secure_air_vent

item(:acid_bath).
  uses(acid(:type => :hcl, :grade => 5)).
  uses(electricity(12))

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

item(:small_power_plant).
  provides(electricity(11)).
  depends_on(:secure_air_vent)