How use optparse gem into rake tasks

optparse+rake.rb

require 'optparse'

namespace :programs do |args|
  desc "Download whatever"
  task :download => [:environment] do

    # USAGE: rake programs:download -- rm
    #-- Setting options $ rake programs:download -- --rm
    options = {}
    option_parser = OptionParser.new
    option_parser.banner = "Usage: rake programs:download -- rm"
    option_parser.on("-r", "--rm","Remove s3 files downloaded") do |value|
      options[:remove] = value
    end
    args = option_parser.order!(ARGV) {}
    option_parser.parse!(args)
    #-- end

    # your code here
  end
end