After running this code, you'll see that our moderator can edit posts successfully:

Post edited 

solid.rb:28:in `<main>': undefined method `delete_post' for #<Moderator:0x007f7f5189a9e0 @blog=#<Blog:0x007f7f5189aa08>> (NoMethodError)

However, when it tries to delete a post it gets an error since we didn't give it access to that method.