[spree-user] a Custom price filter

Hello. i'm trying add my custom price filter

#/lib/venum.rb
module Venum
   def price_filter_venum
     v = Spree::Price.arel_table
     conds = [ [ Spree.t(:under_price, price: format_price(1000)) , v[:
amount].lteq(1000)],
               [ "#{format_price(1000)} - #{format_price(1500)}" , v[:
amount].in(1000..1500)],
               [ "#{format_price(1500)} - #{format_price(1999)}" , v[:
amount].in(1500..1999)],
               [ "#{format_price(2000)} - #{format_price(3000)}" , v[:
amount].in(2000..3000)],
               [ Spree.t(:or_over_price, price: format_price(3000)) , v[:
amount].gteq(3000)]]
     {
         name: Spree.t(:price_range),
         scope: :price_range_any,
         conds: Hash[*conds.flatten],
         labels: conds.map { |k,v| [k, k] }
     }
   end
end


#/config/initializers/spree.rb
require 'venum'
Spree::ProductFilters.include(Venum)

i got error:

/Users/danil/Sites/venum-shop/config/initializers/spree.rb:20:in `<top
(required)>': uninitialized constant Spree::ProductFilters (NameError)


*How should i include this method right?*

later i want change template using deface (to use price_filter_venum
instead price_filter)