```ruby
# frozen_string_literal: true

require 'sass'

module Sass::Script::Functions
  module AppAssetUrl
    def app_asset_url(name)
      assert_type name, :String
      result = %{url("#{app_asset_url_helper(name)}")}
      Sass::Script::String.new(result)
    end

    private

    def app_asset_url_helper(name)
      url_builder = options[:app_asset_url_builder]
      url_builder.app_asset_url(name.value)
    end
  end

  include AppAssetUrl
end

require 'sassc'

module SassC::Script::Functions
  module AppAssetUrl
    def app_asset_url(name)
      raise ArgumentError, "Expected #{name} to be a string" unless name.is_a? Sass::Script::Value::String
      result = %{url("#{app_asset_url_helper(name)}")}
      SassC::Script::String.new(result)
    end

    private

    def app_asset_url_helper(name)
      url_builder = options[:app_asset_url_builder]
      url_builder.app_asset_url(name.value)
    end
  end

  include AppAssetUrl
end
```

Check for the right SassC string type
user
```ruby
# frozen_string_literal: true

require 'sass'

module Sass::Script::Functions
  module AppAssetUrl
    def app_asset_url(name)
      assert_type name, :String
      result = %{url("#{app_asset_url_helper(name)}")}
      Sass::Script::String.new(result)
    end

    private

    def app_asset_url_helper(name)
      url_builder = options[:app_asset_url_builder]
      url_builder.app_asset_url(name.value)
    end
  end

  include AppAssetUrl
end

require 'sassc'

module SassC::Script::Functions
  module AppAssetUrl
    def app_asset_url(name)
      raise ArgumentError, "Expected #{name} to be a string" unless name.is_a? SassC::Script::Value::String
      result = %{url("#{app_asset_url_helper(name)}")}
      SassC::Script::Value::String.new(result)
    end

    private

    def app_asset_url_helper(name)
      url_builder = options[:app_asset_url_builder]
      url_builder.app_asset_url(name.value)
    end
  end

  include AppAssetUrl
end
```
assistant