def url(ref)
      config = self.class.config(@repo, ref)

      lookup = config.keys.inject({}) do |acc, key|
        id = config[key]['id']
        acc[id] = config[key]['url']
        acc
      end

      lookup[@id]
    end
def url(ref)
      config = self.class.config(@repo, ref)

      lookup = config.keys.inject({}) do |acc, key|
        id = config[key]['id']
        acc[id] = config[key]['url']
        acc
      end

      lookup[@id]
    end
The url of this submodule
   +ref+ is the committish that should be used to look up the url

 Returns String