You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: cascade.rb
    path of file: ./repos/brew/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/i18n-1.5.3/lib/i18n/backend
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

# The Cascade module adds the abi
    
      def lookup(locale, key, scope = [], options = EMPTY_HASH)
        return super unless cascade = options[:cascade]

        cascade   = { :step => 1 } unless cascade.is_a?(Hash)
        step      = cascade[:step]   || 1
        offset    = cascade[:offset] || 1
        separator = options[:separator] || I18n.default_separator
        skip_root = cascade.has_key?(:skip_root) ? cascade[:skip_root] : true

        scope = I18n.normalize_keys(nil, key, scope, separator)
        key   = (scope.slice!(-offset, offset) || []).join(separator)

        begin
          result = super
          return result unless result.nil?
          scope = scope.dup
        end while (!scope.empty? || !skip_root) && scope.slice!(-step, step)
      end