title: In Ruby, how can I reference a lambda defined in a module?
body: <p>This code used to work until I put my lambda function in a module.</p>
  
  <p>Here is the lambda function:</p>
  
  <pre><code>module GalleryGenerator
    @add_links_to_descriptions = lambda do |mutable_viewable_content|
      mutable_viewable_content.description = add_links_to_sources(mutable_viewable_content.description)
      return mutable_viewable_content
    end
    #...
  end
  </code></pre>
  
  <p>Here is how it is being used:</p>
  
  <pre><code>include GalleryGenerator
  
  gallery = ViewableGallery.new(gallery_config.title, gallery_config.description, gallery_config.slug, \
  gallery_config.sources, gallery_config.upload_date, gallery_config.map_url, gallery_config.map_title, \
  gallery_config.year, viewable_photos).
  update_using( \
      add_tabs_before_every_description_line(2), \
      @add_links_to_descriptions)
  </code></pre>
  
  <p>That's the error:</p>
  
  <pre><code>/home/mike/Development/Projects/FT/gallery_generator/lib/gallery_generator/viewable_gallery.rb:26:in `block in update_using': undefined method `call' for nil:NilClass (NoMethodError)
  from /home/mike/Development/Projects/FT/gallery_generator/lib/gallery_generator/viewable_gallery.rb:25:in `each'
  from /home/mike/Development/Projects/FT/gallery_generator/lib/gallery_generator/viewable_gallery.rb:25:in `update_using'
  from bin/gallery_generator:32:in `&lt;main&gt;'
  </code></pre>
  
  <p>If the lambda message is not in a module, it all works. I suspect that it's looking for @add_links_to_descriptions in the wrong place now that's in the module... </p>
  
  <p>How can I fix this? Thanks!</p>