def block in rake task

I got undefined local variable or method 'address_geo' for main:Object with the following rake task. What's the problem with it?

include Geokit::Geocoders

namespace :geocode do
  desc "Geocode to get latitude, longitude and address"
  task :all => :environment do
    @spot = Spot.find(:first)
    if @spot.latitude.blank? && !@spot.address.blank?
      puts address_geo
    end

    def address_geo
      arr = []
      arr << address if @spot.address
      arr << city if @spot.city
      arr << country if @spot.country
      arr.reject{|y|y==""}.join(", ")
    end
  end
end