set :animal, "donkey"

task :no_override do
  run "pet #{animal}"
end

task :override do
  set :animal, "pig"
  run "pet #{animal}"
end

task :pet_donkey do
  no_override  #will run "pet donkey"
  override  #will run "pet pig"
end

task :pet_dog do
  set :animal, "dog"
  no_override  #will run "pet dog"
  override  #will run "pet pig"
  no_override # will run "pet dog"
end